The word(s) "back" appears 225 time(s) in 216 verse(s) in Quran in Abdullah Yusuf Ali translation.

(31) That He might cut off a fringe of the Unbelievers or expose them to infamy, and they should then be turned back, frustrated of their purpose.

(32) Muhammad is no more than a messenger: many Were the messenger that passed away before him. If he died or were slain, will ye then Turn back on your heels? If any did turn back on his heels, not the least harm will he do to Allah; but Allah (on the other hand) will swiftly reward those who (serve Him) with gratitude.

(33) O ye who believe! If ye obey the Unbelievers, they will drive you back on your heels, and ye will turn back (from Faith) to your own loss.

(34) Behold! ye were climbing up the high ground, without even casting a side glance at any one, and the Messenger in your rear was calling you back. There did Allah give you one distress after another by way of requital, to teach you not to grieve for (the booty) that had escaped you and for (the ill) that had befallen you. For Allah is well aware of all that ye do.

(35) Those of you who turned back on the day the two hosts Met,-it was Satan who caused them to fail, because of some (evil) they had done. But Allah Has blotted out (their fault): For Allah is Oft-Forgiving, Most Forbearing.

(36) And remember Allah took a covenant from the People of the Book, to make it known and clear to mankind, and not to hide it; but they threw it away behind their backs, and purchased with it some miserable gain! And vile was the bargain they made!

(37) But if ye decide to take one wife in place of another, even if ye had given the latter a whole treasure for dower, Take not the least bit of it back: Would ye take it by slander and manifest wrong?

(38) Allah doth command you to render back your Trusts to those to whom they are due; And when ye judge between man and man, that ye judge with justice: Verily how excellent is the teaching which He giveth you! For Allah is He Who heareth and seeth all things.

(39) Hast thou not turned Thy vision to those who were told to hold back their hands (from fight) but establish regular prayers and spend in regular charity? When (at length) the order for fighting was issued to them, behold! a section of them feared men as - or even more than - they should have feared Allah: They said: "Our Lord! Why hast Thou ordered us to fight? Wouldst Thou not Grant us respite to our (natural) term, near (enough)?" Say: "Short is the enjoyment of this world: the Hereafter is the best for those who do right: Never will ye be dealt with unjustly in the very least!

(40) Others you will find that wish to gain your confidence as well as that of their people: Every time they are sent back to temptation, they succumb thereto: if they withdraw not from you nor give you (guarantees) of peace besides restraining their hands, seize them and slay them wherever ye get them: In their case We have provided you with a clear argument against them.