The word(s) "back" appears 161 time(s) in 150 verse(s) in Quran in Mohsin Khan translation.

(41) And whoever turns his back to them on such a day - unless it be a stratagem of war, or to retreat to a troop (of his own), - he indeed has drawn upon himself wrath from Allah. And his abode is Hell, and worst indeed is that destination!

(42) 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."

(43) If you (O Muhammad صلى الله عليه وسلم) fear treachery from any people throw back (their covenant) to them (so as to be) on equal terms (that there will be no more covenant between you and them). Certainly Allah likes not the treacherous.

(44) Truly Allah has given you victory on many battle fields, and on the Day of Hunain (battle) when you rejoiced at your great number, but it availed you naught and the earth, vast as it is, was straitened for you, then you turned back in flight.

(45) 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."

(46) Those who defame such of the believers who give charity (in Allah's Cause) voluntarily, and such who could not find to give charity (in Allah's Cause) except what is available to them - so they mock at them (believers); Allah will throw back their mockery on them, and they shall have a painful torment.

(47) If Allah brings you back to a party of them (the hypocrites), and they ask your permission to go out (to fight), say: "Never shall you go out with me nor fight an enemy with me; you were pleased to sit (inactive) on the first occasion, then you sit (now) with those who lag behind."

(48) Nor (is there blame) on those who came to you to be provided with mounts, when you said: "I can find no mounts for you," they turned back, while their eyes overflowing with tears of grief that they could not find anything to spend (for Jihad).

(49) They (the hypocrites) will present their excuses to you (Muslims), when you return to them. Say (O Muhammad صلى الله عليه وسلم) "Present no excuses, we shall not believe you. Allah has already informed us of the news concerning you. Allah and His Messenger will observe your deeds. In the end you will be brought back to the All-Knower of the unseen and the seen, then He (Allah) will inform you of what you used to do." [Tafsir At-Tabari]

(50) And among the bedouins around you, some are hypocrites, and so are some among the people of Al-Madinah who persist in hypocrisy; you (O Muhammad صلى الله عليه وسلم) know them not, We know them. We shall punish them twice, and thereafter they shall be brought back to a great (horrible) torment.