And he had over them no authority except [it was decreed] that (34:21)

Almuntakhab Fi Tafsir Alquran Alkarim

In fact AL-Shaytan had no authority over them but We occasioned his attempt to tempt them to identify justly those who affirm with certainty and satisfaction the fundamental truth of the Hereafter and those who are in doubt thereof. And Allah your Creator is indeed Hafizun. (He Keeps a vigilant eye upon the whole and upon all in all)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(34:21) Iblis had no authority over them and whatever happened was in order that We might know him who believes in the Hereafter as distinct from him who is in doubt about it. *36 Your Lord is watchful over everything. *37

And he had over them no authority except [it was decreed] that meaning

*36) That is, `Iblis did not have the power to have forcibly misled these people to the way of God's disobedience although they had wanted to adopt His obedience. Allah had only given him the power that he may seduce and mislead them and make aII such people his followers, who may like to follow him of their own accord. And Iblis was provided these opportunities for seduction so that the believers of the Hereafter were distinguished from those who entertained doubts about its coming. "
In other words, this Divine statement makes the truth explicit that nothing in this world other than belief in the Hereafter can ensure man's adherence to the right way. If a man disbelieves that he is to be raised back to life after death and has to render an account of his deeds before his God, he will certainly be misled and go astray, for he will never be able to develop in himself the sense of .responsibility which alone can make him adhere to the right way. That is why the artifice of Satan by which he ensnares man is that he makes him heedless of the Hereafter. The one who escapes this satanic enticement can never agree that he should sacrifice the interests of his real everlasting life to the interests of the transient life of the world. On the contrary, the one who disbelieves in the Hereafter under the evil influence of Satan, or at least entertains doubts about it, can never be induced to withdraw from the cash bargain being made in this world only due to the apprehension that it might cause loss in some later life. Whoever has gone astray in the world, has gone astray only due to the denial of the Hereafter, or some suspicion about it; and whoever has adopted righteousness has done so because his righteous deeds have issued from his belief in the Hereafter.
*37) To understand fully the allusions made in the Qur'an to the history of the Sabaeans, one should also keep in view the information that has been obtained through other historical sources about this nation.
Historically, Saba' were a great nation of Southern Arabia. which comprised some large tribes. Imam Ahmad, Ibn Abi Hatim, Ibn 'Abd al-Barr and Tirmidhi have related from the Holy Prophet that Saba was the name of an Arab, from whose race issued the following tribes of Arabia: Kindah. Himyar, Azd, Ash ariyyin, Madhhij, Anmar (with its two branches: Khath'am and Bajilah), 'Amilah, Judham, Lakhm and Ghassan.
Since antiquity this Arabian nation has been well known to the rest of the world. Ur inscriptions of 2500 B.C. mention it by the name of Sabom. Then in the Babylonian and Assyrian inscriptions and also in the Bible it has been mentioned several times. (See, for instance, Psalms 72:15; Jeremiah 6: 20; Ezekiel 27:22, 38: 13; Job 6: 19). The Greek and Roman historians and the geographer Theo-phrastus (288 B.C.) have mentioned it continuously for many centuries of the Christian era since before Christ. .
Its home was the south-western corner of the Arabian peninsula, now called al-Yaman. Its rise to prominence started in 1100 B.C. In the time of the Prophets David and Solomon the Sabaeans had become world fatuous as a wealthy people. In the beginning they were a sun-worshipping nation. Then, when their queen affirmed faith at the hand of the Prophet Solomon (965-926 B.C.) probably most of them became Muslims. But then in some unknown later period they again began to worship gods and goddesses tike Almaqah (the moon-god), 'A thtar (Venus), Dhat Hamim, Dhat Bad'an (the sun-god), Harmatam or Harimat and many others. Almaqah was their chief deity, and the kings made claim to the people's obedience as representatives of this deity. Many inscriptions have been unearthed in the Yaman, which show that the whole land abounded in the temples of these gods, especially of Almaqah, and thanks giving services for them were held at every important event.
As a result of the modern archaeological researches about 3,000 inscriptions have been discovered, which throw a good deal of light on the history of this nation. Besides these, if the information yielded by the Arabian traditionists and the Roman and Greek historians is compiled, a detailed history of this nation can be prepared. According to this information the following are the important periods of its history:
(1) The Pre-mid-seventh Century Period: In this period Mukarrib was the title of the Sabaean kings. Probably a synonym of Muqarrib, it signified that the kings regarded themselves as the link between men and gods; or, in other words, they were the priest-kings. Their capital was Sirwah, whose ruins are found at a day's journey to the west of Maa'rib, and are now called al-Kharibah. The foundations of the great Maa'rib dam were laid in this period: then the different kings extended it from time to time.
(2) 650 B. C. to 115 B. C. : In this period the Sabaean kings discarded Mukarrib and adopted the title of Malik (king), which signified that theocracy was replaced by secular kingship. They left Sirwah and made Maa'rib their capital and extended it in every way. This place lay 3900 feet above the sea, and is some 60 miles east of San'a'. Even today its nuns bear evidence that it was once the centre of a highly civilized nation.
(3) 115 B. C. to 300 A.D. : In this period the Sabaean kingdom fell under the domination of the tribe of Himyar, a more numerous tribe of Saba. They discarded Maa'rib and made their central place, Raydan, their capital, which later became known as Zafar. Its nuns can still be seen on a circular hill near the modern city of Yarim. Close by it there resides a small tribe by the name of Hinmar, perhaps the remnant of the great nation which was once well known throughout the world for its glory and grandeur. In the same period the word Yamanat and Yamanat began to be used for the first time for a part of the kingdom, which gradually became Yaman and the name of the entire land, which extends from `Asir to Aden and from Bab al-Mandab to Hadramaut. During this very period the decline of the Sabaean began.
(4) 300 A.D. to the rise, of Islam :This is the period of the Sabaea's destruction. They started fighting civil wars, which provided occasion for external intervention. This resulted in the decline in their trade and their agriculture and even loss of political freedom. Taking advantage of the internal conflicts between the Himyarites and other tribes, the Abyssinians occupied the Yaman and ruled it briefly from 340 A.D. to 378 A.D. Then, though political freedom was restored, breaches began to appear in the great dam of Maa'rib, which in 450 or 451 A.D. led to the catastrophe occasioned by the "bursting of the dam" as has been referred to in verse 16 above. Although after it till the time of Abraha the dam was extensively repaired, the population that had dispersed could not be brought back, nor could the ruined system of irrigation and agriculture be restored. In 523 A.D., dhu-Nuwas, the Jewish king of the Yaman, carried out the great massacre of the Christians of Najran, which has been referred to in the Qur'an under "ashab al-ukhdud" (LXXXV: 4). In retaliation, the Christian kingdom of Abyssinia invaded Yaman and occupied the whole land. Later the Abyssinian governor of Yaman, Abrahah, in a bid to put an end to the central position of the Ka`bah and to bring the whole of western Arabia into the sphere of the ByzantineAbyssinian influence invaded Makkah in 570 or 571 A.D., a few days before the birth of the Holy Prophet Muhammad (upon whom be Allah's peace). The Abyssinian army was completely destroyed as alluded to under ashab al-fil in the Qur'an. At last, in 575 A.D. Yaman fell to the Iranians; their rule came to an end in 628 A.D. when their governor Badhan embraced Islam.
The Sabaeans owed their prosperity to two main factors: agriculture and commerce. They had developed their agriculture by means of a wonderful irrigation system unknown in the ancient world except in Babylon. There were no natural rivers in their land; in the rainy season small hill-torrents rose on which they had built dams every where in the country and collected water in small lakes from which they had taken out canals to water their lands. This had virtually turned the whole country into a vast garden as mentioned in the Qur'an. The largest reservoir was the lake which had been formed by the construction of a dam on the opening in the Jabal Balaq near Maa`rib. But when Allah caused His favours to be turned away from them, the great dam burst in the mid-fifth century A.D. and the resultant floods went on breaking one dam after the other on the way, destroying the entire irrigation system, which could never again be restored.
For commerce the Sabaeans had been blessed by God with the most favourable geographical position of which they took full advantage. For more than a thousand years they monopolised the means of trade between the East and the West. On the one hand, they received silk from China, spices from Indonesia and Malabar, fabrics and swords from India, negro slaves, monkeys, ostrich feathers and ivory from East Africa at their ports, and on the other, they transported this merchandise to the Egyptian and Syrian marts, to be supplied onward to Rome and Greece. Besides, they themselves were great producers of frankincense and myrrh and other perfumes, which were in great demand in Egypt and Syria and in Rome and Greece.
Two great routes exiated for this international trade: the sea route and the land route. The maritime trade remained in the Sabaeans' control for more than a thousand years for they alone knew the mysteries of the Red Sea monsoons, breakers and rocks and the anchorages, and no other nation could risk navigation through these dangerous waters. Through this maritime route they took their trade goods to the harbours of Jordan and Egypt. The land routes from Aden and Hadramaut joined at Ma'arib, from where a highway led to Petra through Makkah, Jeddah, Yathrib, AI-`Ula, Tabuk and Aylah, forking at the northern end to Egypt and Syria. Along this land route, a number of Sabaean colonies had been established right from the Yaman to the borders of Syria, as mentioned in the Qur'an, and trade caravans passed by these day and night. The signs of many of these colonies still exist on this route from which the Sabaean and the Himyarite inscriptions are being discovered.
After the first century after Christ Sabaean trade began w suffer a decline. When the Greek, and then the Roman, kingdoms were established in the Middle East, the citizens began complaining of the high prices that the Arabian traders were charging for the oriental goods because of their monopoly, and urged their governments to take the initiative to break their supremacy in the sea trade. Thus, in the beginning, Ptolemy II (985-246 B.C.), the Greek ruler of Egypt, reopened the Nile-Red Sea canal originally dug by Pharaoh Sesostris some seventeen centuries previously. Consequently, it was through this canal that the Egyptian fleet entered the Red Sea for the first time, but it could not succeed much against the Sabaeans. When Egypt fell to the Romans they brought a stronger merchant marine into the Red Sea and put a naval fleet at its back. The Sabaeans could not withstand this force. Consequently, the Romans set up their trade colonies at every seaport, arranged supplies for the ships and also stationed their military troops wherever possible. At last, the time came when Aden passed under the military occupation of the Romans. In this connection, the Roman and the Abyssinian kingdoms also entered secret pacts against the Sabaeans, which ultimately deprived this nation of its political freedom as well.
After losing control over maritime trade the Sabaeans were left with trade over the land route only, but many factors combined to gradually break its back too. First, the Nabataeans ousted them from all the colonies of the upper Hejaz and Jordan, from Petra to Al-`Ula. Then in 106 A.D. the Romans put an end to the Nabataean kingdom and captured all the Syrian and Jordanian territories up to the Hejaz. After this Abyssinia and Rome jointly tried to ruin the Sabaean trade completely by taking advantage of their internal conflicts. That is why the Abyssinians intervened in the Yaman again and again, till at last they brought the whole land under their occupation.
Thus, Allah's wrath caused this nation to be toppled from the heights of glory and prosperity into oblivion from which they were never able to rise again. There was a time when the Greeks and the Romans felt tempted when they heard of the legendary wealth of this people. Strabo writes, "The Sabaeans use gold and silver utensils and even the ceilings, walls and doors of their houses are bedecked with ivory, gold, silver and jewels." Pliny says, "The whole wealth of Rome and Persia is flowing into Sabaean hands. They are the richest people of the world today, and their fertile land abounds in gardens, crops and cattle." Artemidorus says, "These people roll in luxury. They burn cinnemon, sandalwood and other sweet smelling wood as fuel. " Likewise, other Greek historians relate that the passengers passing by their shores can smell the perfumes of their land in the merchant ships at sea. For the first time in history they built a skyscraper, called the castle of Ghumdan, on the hill top in San`a'. This citadel, according to the Arab historians, had twenty storeys, each storey being 36 feet high. Thus did they prosper and enjoy life as long as Allah favoured them with His bounties. At last, when they transgressed aII limits in their ingratitude, the Almighty Allah also withdrew His attention, and they were so utterly destroyed as if they had never existed at all.
 

And he had over them no authority except [it was decreed] that meaning in Urdu

ابلیس کو اُن پر کوئی اقتدار حاصل نہ تھا مگر جو کچھ ہوا وہ اس لیے ہوا کہ ہم یہ دیکھنا چاہتے تھے کہ کون آخرت کا ماننے والا ہے اور کون اس کی طرف سے شک میں پڑا ہوا ہے تیرا رب ہر چیز پر نگران ہے