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

(181) Behold, ye are those invited to spend (of your substance) in the Way of Allah: But among you are some that are niggardly. But any who are niggardly are so at the expense of their own souls. But Allah is free of all wants, and it is ye that are needy. If ye turn back (from the Path), He will substitute in your stead another people; then they would not be like you!

(182) Say to the desert Arabs who lagged behind: "Ye shall be summoned (to fight) against a people given to vehement war: then shall ye fight, or they shall submit. Then if ye show obedience, Allah will grant you a goodly reward, but if ye turn back as ye did before, He will punish you with a grievous Penalty."

(183) No blame is there on the blind, nor is there blame on the lame, nor on one ill (if he joins not the war): But he that obeys Allah and his Messenger,- (Allah) will admit him to Gardens beneath which rivers flow; and he who turns back, (Allah) will punish him with a grievous Penalty.

(184) If the Unbelievers should fight you, they would certainly turn their backs; then would they find neither protector nor helper.

(185) They are the ones who denied Revelation and hindered you from the Sacred Mosque and the sacrificial animals, detained from reaching their place of sacrifice. Had there not been believing men and believing women whom ye did not know that ye were trampling down and on whose account a crime would have accrued to you without (your) knowledge, (Allah would have allowed you to force your way, but He held back your hands) that He may admit to His Mercy whom He will. If they had been apart, We should certainly have punished the Unbelievers among them with a grievous Punishment.

(186) O ye who believe! Avoid suspicion as much (as possible): for suspicion in some cases is a sin: And spy not on each other behind their backs. Would any of you like to eat the flesh of his dead brother? Nay, ye would abhor it... But fear Allah: For Allah is Oft-Returning, Most Merciful.

(187) But (Pharaoh) turned back with his Chiefs, and said, "A sorcerer, or one possessed!"

(188) Seest thou one who turns back,

(189) Soon will their multitude be put to flight, and they will show their backs.

(190) Call back the soul, if ye are true (in the claim of independence)?