The word(s) "back" appears 101 time(s) in 98 verse(s) in Quran in Muhammad Pickthal translation.

(31) On the day when it will (all) be heated in the fire of hell, and their foreheads and their flanks and their backs will be branded therewith (and it will be said unto them): Here is that which ye hoarded for yourselves. Now taste of what ye used to hoard.

(32) And if they had wished to go forth they would assuredly have made ready some equipment, but Allah was averse to their being sent forth and held them back and it was said (unto them): Sit ye with the sedentary!

(33) If Allah bring thee back (from the campaign) unto a party of them and they ask of thee leave to go out (to fight), then say unto them: Ye shall never more go out with me nor fight with me against a foe. Ye were content with sitting still the first time. So sit still, with the useless.

(34) Nor unto those whom, when they came to thee (asking) that thou shouldst mount them, thou didst tell: I cannot find whereon to mount you. They turned back with eyes flowing with tears, for sorrow that they could not find the means to spend.

(35) They will make excuse to you (Muslims) when ye return unto them. Say: Make no excuse, for we shall not believe you. Allah hath told us tidings of you. Allah and His messenger will see your conduct, and then ye will be brought back unto Him Who knoweth the Invisible as well as the Visible, and He will tell you what ye used to do.

(36) And say (unto them): Act! Allah will behold your actions, and (so will) His messenger and the believers, and ye will be brought back to the Knower of the Invisible and the Visible, and He will tell you what ye used to do.

(37) On the day when We gather them all together, then We say unto those who ascribed partners (unto Us): Stand back, ye and your (pretended) partners (of Allah)! And We separate them, the one from the other, and their (pretended) partners say: It was not us ye worshipped.

(38) My counsel will not profit you if I were minded to advise you, if Allah's will is to keep you astray. He is your Lord and unto Him ye will be brought back.

(39) He said: O my people! Bethink you: if I am (acting) on a clear proof from my Lord and He sustaineth me with fair sustenance from Him (how can I concede aught to you)? I desire not to do behind your backs that which I ask you not to do. I desire naught save reform so far as I am able. My welfare is only in Allah. In Him I trust and unto Him I turn (repentant).

(40) He said unto his young men: Place their merchandise in their saddlebags, so that they may know it when they go back to their folk, and so will come again.