The word(s) "backs" appears 26 time(s) in 26 verse(s) in Quran in Mohsin Khan translation.

(1) And (remember) when We took a covenant from the Children of Israel, (saying): Worship none but Allah (Alone) and be dutiful and good to parents, and to kindred, and to orphans and Al-Masakin (the poor), and speak good to people [i.e. enjoin righteousness and forbid evil, and say the truth about Muhammad صلى الله عليه وسلم], and perform As-Salat (Iqamat-as-Salat), and give Zakat. Then you slid back, except a few of you, while you are backsliders. (Tafsir Al-Qurtubi).

(2) And when there came to them a Messenger from Allah (i.e. Muhammad صلى الله عليه وسلم) confirming what was with them, a party of those who were given the Scripture threw away the Book of Allah behind their backs as if they did not know!

(3) They will do you no harm, barring a trifling annoyance; and if they fight against you, they will show you their backs, and they will not be helped.

(4) Those of you who turned back on the day the two hosts met (i.e. the battle of Uhud), it was Shaitan (Satan) who caused them to backslide (run away from the battlefield) because of some (sins) they had earned. But Allah, indeed, has forgiven them. Surely, Allah is Oft-Forgiving, Most Forbearing.

(5) (And remember) when Allah took a covenant from those who were given the Scripture (Jews and Christians) to make it (the news of the coming of Prophet Muhammad صلى الله عليه وسلم and the religious knowledge) 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 indeed worst is that which they bought.

(6) They indeed are losers who denied their Meeting with Allah, until all of a sudden, the Hour (signs of death) is on them, and they say: "Alas for us that we gave no thought to it," while they will bear their burdens on their backs; and evil indeed are the burdens that they will bear!

(7) And unto those who are Jews, We forbade every (animal) with undivided hoof, and We forbade them the fat of the ox and the sheep except what adheres to their backs or their entrails, or is mixed up with a bone. Thus We recompensed them for their rebellion [committing crimes like murdering the Prophets and eating of Riba (usury)]. And verily, We are Truthful.

(8) O you who believe! When you meet those who disbelieve, in a battle-field, never turn your backs to them.

(9) And if you could see when the angels take away the souls of those who disbelieve (at death); they smite their faces and their backs, (saying): "Taste the punishment of the blazing Fire."

(10) On the Day when that (Al-Kanz: money, gold and silver the Zakat of which has not been paid) will be heated in the Fire of Hell and with it will be branded their foreheads, their flanks, and their backs, (and it will be said unto them): "This is the treasure which you hoarded for yourselves. Now taste of what you used to hoard."