And when you travel throughout the land, there is no blame upon (4:101)

Almuntakhab Fi Tafsir Alquran Alkarim

And if you journey into a foreign land, be it in the cause of Allah or for any other purpose, you incur no guilt if you should shorten your prayer (one time kneeling, twice prostrating performed twice instead of three or four times), that is if you fear you might be exposed to a willfully inflicted injury by those who are an open enemy of the faith. Therefore, be cautious; the infidels are indeed your avowed enemy

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

(4:101)When you go forth journeying in the land, there is no blame on you if you shorten the Prayer, *132 (especially) if you fear that the unbelievers might cause you harm. *133 Surely the unbelievers are your open enemies.

And when you travel throughout the land, there is no blame upon meaning

*132). Shortening Prayers (qasr) while travelling in peace-time consists of praying two rak'ahs at those appointed times when one is normally required to pray four rak'ahs. The form of qasr during a state of war has not been specified. Prayers should, therefore, be performed as circumstances permit. People should pray in congregation if possible, otherwise individually. If it is not possible to turn towards the qiblah, one may keep the direction in which one happens to be facing. One may even pray while seated either on the back of an animal or on a vehicle. If actual bowing and prostrating are not possible, they may be performed with hand signals. If absolutely necessary, one may even pray while walking. One may also pray even though one's clothes are soiled with blood. If, in spite of these relaxations, a man still fails to manage to perform a Prayer within the prescribed time, he may defer it, following the precedent set by the Prophet (peace be on him) during the Battle of the Ditch.
There is disagreement as to whether one should also perform the sunnah (recommended) Prayers, or confine oneself to the obligatory ones. It is established that the practice of the Prophet (peace be on him) was to keep up the sunnah connected with the fajr (morning) Prayers, and with the witr in the 'isha' (evening) Prayers. At the other prescribed times, he performed only the obligatory Prayers. He did, however, perform the nafl (supererogatory) Prayers whenever he had the chance to do so, sometimes even while he was mounted. For this reason 'Abd Allah b. 'Umar expressed the opinion that one ought not to perform the sunnah Prayers while travelling, except for the sunnah in the fajr Prayers. But a majority of scholars consider both the performance and the omission of these Prayers as equally permissible, leaving the matter entirely to the discretion of the individual. The opinion held by the Hanafi school, however, is that it is preferable for a traveller actually on the move to omit the sunnah Prayers, but when he makes an overnight stop and is at his ease (even though in the legal sense he may still be a traveller), their performance is preferable.
According to some eminent jurists, journeys on which one may resort to qasr are those characterized as being fi sabil Allah (in the cause of God), such as military expeditions, Pilgrimage, the quest for knowledge, and so on. This is the judgement of 'Abd Allah b. 'Umar, 'Abd Allah b. Mas'ud and 'Ata'. On the other hand, Shafi'i and Ahmad b. Hanbal are of the view that such permission extends to all journeys undertaken for lawful purposes, though not to those undertaken for unlawful purposes: indeed, if one travels for illegitimate purposes, one has no right whatever to benefit from the relaxation of qasr. Hanafi jurists, however, do not connect qasr with the purpose of the journey; they consider it lawful on all journeys, regardless of the purposes for which they are undertaken. They hold that a traveller may be either rewarded or punished by God, depending on his purpose in travelling. That, however, has nothing to do with the permissibility of qasr. (See the commentaries on the verse by Qurtubi, Ibn Kathir and Jassas. See also Ibn Rushd, Biddy at al-Mujtahid, vol. 1, p. 163 - Ed.)
Other eminent jurists have inferred from the words: 'And there is no blame on you . . . ' that qasr is not obligatory for a traveller: it is merely permitted. A person may avail himself of it if he chooses, and he may also perform his Prayers normally if he so wishes. This is the view of Shafi'i, even though he considers qasr recommended and holds its omission to be tantamount to failure to adopt the preferable alternative. According to Ahmad b. Hanbal, however, while qasr is not obligatory, its omission falls under the category of disapproved acts. In Abu Hanifah's opinion, qasr is obligatory, and according to one report, Malik is of the same opinion. (See the commentaries on the verse by Qurtubi, Jassas and Ibn al-'Arabi. See also al-Fiqh 'aid al-Madhdhib al-Arba'ah, vol. 1, p. 471, and n. 1, pp. 471-3 and Ibn Rushd, vol. 1, p. 161 - Ed.) It is established by the Hadith that the Prophet (peace be on him) always shortened his Prayers during his journeys. There is no reliable tradition to the effect that the Prophet (peace be on him) ever prayed four full rak'ahs in these circumstances. Ibn 'Umar states that he accompanied the Prophet (peace be on him) as well as Abu Bakr, 'Umar and 'Uthman on their journeys, and never saw any of them fail to shorten their Prayers. A number of authentic traditions which have come down from Ibn 'Abbas and several other Companions corroborate this. When 'Uthman prayed four rak'ahs in Mina on the occasion of Hajj, some Companions objected to his not shortening the Prayer. 'Uthman convinced them that he had not made any mistake in so doing by arguing that he had got married in Makka and he had heard from the Prophet (peace be on him) that the place a person married in was in a sense his home. In that respect he was, therefore, not a traveller. (See the commentaries on the verse by Qurtubi, Jassas and Ibn Kathir, and the chapters on 'Salat al-Qasr' in the major collections of Hadith - Ed.)
In opposition to these numerous traditions are two from 'A'ishah which indicate that it is equally valid both to shorten the Prayers and to do them in full. These traditions, however, have weak links in their transmission and are also opposed to the authenticated practice of 'A'ishah herself. It is also true that there are intermediary states between travel and non-travel. During a temporary stop, it is quite proper for a man to shorten his Prayers on some occasions and on others to complete them. It depends upon the circumstances. It is probably in this context that 'A'ishah states that the Prophet (peace be on him) sometimes shortened his Prayers and sometimes performed them in full.
The Qur'anic expression in the verse 'there shall be no blame' also occurs in the Qur'anic verse on the ritual of running between Safa and Marwah (see Surah al-Baqarah 2: 158). The actual words used in both verses apparently mean that these acts were not blameworthy even though the running, as we know, is part of the prescribed rites of Pilgrimage and is obligatory: We can appreciate the significance of both these Qur'anic verses if we remember that the purpose in each case is to dispel the misunderstanding that the acts concerned might either entail some sin or jeopardize a man's reward.
Another question in. regard to qasr is: What is the minimum travelling distance in which Prayers may be shortened? The Zahiri school recognizes no limit at all: any travelling validates the shortening of Prayers. According to Malik, however, one may not shorten Prayers if the distance involved is either less than forty-eight miles (seventy-seven kilometers) or involves travelling for less than a day and a night. This is also the opinion of Ahmad b. Hanbal and Ibn 'Abbas and a statement in support of it has also come down from Shafi'i. The Companion Anas considers it permissible to shorten Prayers if the travelling distance is fifteen miles. Awza'i, Zuhri and 'Umar consider one day's travelling to be sufficient; Hasan al-Basri says that the journey should be two days long, and Abu Yusuf says that it should be more than two days. According to Abu Hanifah, one may shorten the Prayers on any journey in which one has to travel for three days either on foot or by camel, i.e. a distance of eighteen farsakh. Ibn 'Umar, Ibn Mas'ud and 'Uthman agree with this view. (See the commentary on the verse by Qurtubi and Jassas. See also al-Fiqh 'aid al-Madhahib al-Arba'ah, vol. 1, pp. 472 ff. and Ibn Rushd, vol. 1, pp. 163 ff. - Ed.)
If one stops over en route to one's destination, how long may one stay in one place and still be allowed to shorten one's Prayers? On this question, too, a variety of opinions have been expressed. Ahmad b. Hanbal is of the opinion that if a man decides to stay for four days, he should perform his Prayers in full. Malik and Shafi'i are of the opinion that a man may not shorten his Prayers if he decides to stay at a place for more than four days. Awza'i and Abu Hanifah are respectively of the opinion that if a person intends to stay at a place for more than thirteen or fifteen days, he should pray in full. No categorical injunction has come down from the Prophet (peace be on him) on this matter. All jurists agree, however, that if a man has been held up somewhere and cannot proceed because of some constraint, he may shorten his Prayers indefinitely provided he is in a constant state of readiness to undertake the journey back to his home as soon as the constraint is removed. Instances are reported of Companions who continued to shorten their Prayers for two years in this kind of circumstance. Treating the situation of a prisoner as analogous to this, Ahmad b. Hanbal holds that he may shorten his Prayers throughout the period of his imprisonment. (For legal discussions on the questions discussed here see the commentaries on the verse by Ibn Kathir, Jassas, Qurtubi and Ibn al-'Arabi. See also Ibn Rushd, vol. 1, pp. 160-5 - Ed.)
*133). The Zahiris and Khawarij have interpreted this to signify that the injunction of shortening Prayers is confined to war-time alone and that it is against the Qur'an to shorten Prayers while travelling in peace-time. But it is established by an authentic tradition that when 'Umar mentioned this misgiving to the Prophet (peace be on him), he said: "This is a charitable gift to you from God, so accept His charitable gift.' (Muslim, 'Salat al-Musafirin', 12; Abu Da'ud, 'Salat al-Safar', 1; Ahmad b. Hanbal, Musnad, vol. 3, pp. 129 and 190 - Ed.) It is more or less established by an overwhelmingly large number of traditions that the Prophet (peace be on him) shortened his Prayers in times of both war and peace. Ibn 'Abbas states categorically that the Prophet (peace be on him) left Madina with the intention of performing Pilgrimage to the Ka'bah, and during this journey he prayed two rak'ahs (instead of four) even though he could have nothing to fear except God. (See Nasa'i, 'Taqsir al-Salah', 1 - Ed.) It is for this reason that I have added the word 'especially' in brackets to the text of the translation:
 

And when you travel throughout the land, there is no blame upon meaning in Urdu

اور جب تم لوگ سفر کے لیے نکلو تو کوئی مضائقہ نہیں اگر نماز میں اختصار کر دو (خصوصاً) جبکہ تمہیں اندیشہ ہو کہ کافر تمہیں ستائیں گے کیونکہ وہ کھلم کھلا تمہاری دشمنی پر تلے ہوئے ہیں