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

(1) And (remember) when We made a covenant with the Children of Israel, (saying): Worship none save Allah (only), and be good to parents and to kindred and to orphans and the needy, and speak kindly to mankind; and establish worship and pay the poor-due. Then, after that, ye slid back, save a few of you, being averse.

(2) And when there cometh unto them a messenger from Allah, confirming that which they possess, a party of those who have received the Scripture fling the Scripture of Allah behind their backs as if they knew not,

(3) They ask thee, (O Muhammad), of new moons, say: They are fixed seasons for mankind and for the pilgrimage. It is not righteousness that ye go to houses by the backs thereof (as do the idolaters at certain seasons), but the righteous man is he who wardeth off (evil). So go to houses by the gates thereof, and observe your duty to Allah, that ye may be successful.

(4) And if ye slide back after the clear proofs have come unto you, then know that Allah is Mighty, Wise.

(5) Wait they for naught else than that Allah should come unto them in the shadows of the clouds with the angels? Then the case would be already judged. All cases go back to Allah (for judgment).

(6) Women who are divorced shall wait, keeping themselves apart, three (monthly) courses. And it is not lawful for them that they should conceal that which Allah hath created in their wombs if they are believers in Allah and the Last Day. And their husbands would do better to take them back in that case if they desire a reconciliation. And they (women) have rights similar to those (of men) over them in kindness, and men are a degree above them. Allah is Mighty, Wise.

(7) And if ye go in fear, then (pray) standing or on horseback. And when ye are again in safety, remember Allah, as He hath taught you that which (heretofore) ye knew not.

(8) Bethink thee (O Muhammad) of those of old, who went forth from their habitations in their thousands, fearing death, and Allah said unto them: Die; and then He brought them back to life. Lo! Allah is a Lord of Kindness to mankind, but most of mankind give not thanks.

(9) Or (bethink thee of) the like of him who, passing by a township which had fallen into utter ruin, exclaimed: How shall Allah give this township life after its death? And Allah made him die a hundred years, then brought him back to life. He said: How long hast thou tarried? (The man) said: I have tarried a day or part of a day. (He) said: Nay, but thou hast tarried for a hundred years. Just look at thy food and drink which have not rotted! Look at thine ass! And, that We may make thee a token unto mankind, look at the bones, how We adjust them and then cover them with flesh! And when (the matter) became clear unto him, he said: I know now that Allah is Able to do all things.

(10) And guard yourselves against a day in which ye will be brought back to Allah. Then every soul will be paid in full that which it hath earned, and they will not be wronged.