And he has failed who instills it [with corruption]. (91:10)

Almuntakhab Fi Tafsir Alquran Alkarim

And a loser indeed will be he who has perverted himself and by the hand of sin he is bound

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

(91:10) and he who suppresses it will be ruined. *6

And he has failed who instills it [with corruption]. meaning

*6) This is for which an oath has been sworn by the things mentioned in the above verses. Let us now consider how those things bear upon it. The rule that Allah has followed in the Qur'an is that to bear testimony to the truths that He wants to impress on the human mind, he cites some of the most conspicuous, common-place things which every man sees in his surroundings, or in his own self. Accordingly here, pairs of contradictory things have been cited, each unlike the other in its effects and results, rather opposite and reverse. The first pair is of the sun and the moon. The light of the sun is intensely bright and also hot. As against it the moon has no light of its own. Even if it is there in the sky when the sun shines, it is without light. It shines when the sun hides, and even then its light is neither so bright that it may change the night into day nor is there any heat in it that it may have the same effect as the sun's light. Nevertheless, it has its own effects which are quite different from the effects of the sun. Likewise, there is the pair of the day and the night. Each is the reverse of the other. The effects and results of each are so different from the other that no one can say they are alike; so much so that even a most foolish person cannot possibly say that the day's being the day or the ,night's being the night dces not make any difference. Likewise, there is the pair of the sky and the earth; the former has been raised high by the Creator and the latter spread like a carpet beneath it. Although both are serving the same universe, its system and expediencies, yet there is a world of difference between their functions and their effects and results. After citing these universal evidences, man's own self has been considered, and it has been said that after balancing it with suitable combination of the limbs, senses and mental powers and faculties the Creator has placed in it tendencies, inclinations and motives to both good and evil, which are contradictory to each other, and made him understand by inspiration the distinction between the two: that one is fujur, which is evil, and the other is tagva, which is good. Now, if the sun and the moon, the day and the night, the earth and the heaven, are not alike but necessarily different from each other in their effects and results, how can fujur and taqva of the self be alike in spite of being reverse of each other? Man himself in this world does not regard and acknowledge the good and the evil as equal, no matter what criteria of good and evil he might have devised for himself according to his self-propounded philosophies. In any case, about whatever he regards as good, he holds the opinion that it is appreciable and worthy of praise, reward and recompense. On the contrary, about whatever he regards as evil, it is his own objective opinion that it is worthy of condemnation and punishment. But the real judgement does not lie with man; it lies with the Creator, Who has inspired man with his fujur and taqva. The fujur is that which is fujur in the sight of the Creator and the tagva that which is tagva in His sight, and both have separate results in the sight of the Creator. The result of the one is that he who purifies his self, should attain to eternal success, and the result of the, other is that he who suppresses his self, should be a failure.
Tazkiyah means to purify, develop and cultivate. In the context it clearly moans the one who purifies his self of fujur and develops it to the level of tagva and cultivates in it the ,good, will attain to eternal success. As against this; the word dassaha has been used, the infinitive of which is tadsiyah, which means to suppress, conceal, seduce and lead astray. The meaning of this also becomes clear from the context; i. e. the one who suppresses the tendency in his self towards good instead of developing and cultivating it, who seduces it into doing evil, and makes fujur dominate over taqva so as to cover it up completely like the dead body which is buried and covered with earth, will be a failure. Some commentators have interpreted this verse to mean: "Truly successful was he whom (whose self) Allah purified .and a failure he whom (whose self) Allah suppressed." But this commentary is, firstly, opposed to the style of the Qur'an in view of the language, for if Allah had meant to say this, He would have said: "Truly successful was the self which Allah purified and a failure the self which Allah suppressed;" secondly, this commentary clashes with the other statements of the Qur'an on this subject. In Surah Al-A`la, Allah says: "Truly successful was he who adopted purity." (v. 14). In Surah `Abasa, Allah has addressed His Holy Messenger, saying: "And. you would not be responsible if he did not adopt purity " In both these verses, adoption of purity has been regarded as an act of man. Besides, the truth stated at many places in the Qur'an is that man in this world is being put to the test. For example, in Surah Ad-Dahr, it is said: "We created man from a mixed sperm-drop, to try him, and so We made him capable of hearing and seeing." (v. 2) In Surah AlMulk it is stated: "Who created death and life that he may try you to see which of you is best in deeds. (v. 2) Now, obviously, if the examiner at the outset encourages one candidate and discourages the other, the test would he a farce. Therefore, the correct commentary is that which Qatadah, `Ikrimah, Mujahid and Sa`id bin Jubair have given, saying that the subject zakkaha and dassaha is man and not God. As for the Hadith which Ibn Abi Hatim has related on the authority of Juwaybir bin Sa`id from Dahhak from Ibn `Abbas, saying that the Holy Prophet (upon whom be peace) himself interpreted this verse to mean: "Truly successful was the self whom the Almighty Allah purified"; this saying is not confirmed to be from the Holy Prophet, for its one reporter Juwaybir, has been rejected as a narrator of Hadith, and Dahhak did not meet Ibn `Abbas. However, the Hadith which Imam Ahmad, Muslim, Nasa'i and Ibn Abi Shaibah have related on the authority of Hadrat Zaid bin Arqam, is correct which says that the Holy Prophet used to pray: "O Allah, grant my self its taqva and purify it: You alone are the best to purify it; You alone are its Guardian and Master. " In almost similar words, this supplication of the Holy Prophet has been related by Tabarani Ibn Marduyah and lbn al-Mundhir from Hadrat `Abdullah bin `Abbas and Imam Ahmad from Hadrat `A'ishah. It actually means that man can only desire and seek tagva and tazkiyah; as for its attainment, it depends in any case on Allah's grace and,favour alone. And the same also is we of tadsiyah: Allah does not suppress a self forcibly, but when a man is resolved on iniquity, Allah deprives him of the grace of tagva and tazbyab, 'and leaves him alone to suppress and bury his self under nay heap of filth he likes.
 

And he has failed who instills it [with corruption]. meaning in Urdu

اور نامراد ہوا وہ جس نے اُس کو دبا دیا