The word(s) "which" appears 609 time(s) in 551 verse(s) in Quran in Abdullah Yusuf Ali translation.

(131) But Allah did pour His calm on the Messenger and on the Believers, and sent down forces which ye saw not: He punished the Unbelievers; thus doth He reward those without Faith.

(132) Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Messenger, nor acknowledge the religion of Truth, (even if they are) of the People of the Book, until they pay the Jizya with willing submission, and feel themselves subdued.

(133) On the Day when heat will be produced out of that (wealth) in the fire of Hell, and with it will be branded their foreheads, their flanks, and their backs, their flanks, and their backs.- "This is the (treasure) which ye buried for yourselves: taste ye, then, the (treasures) ye buried!"

(134) If ye help not (your leader), (it is no matter): for Allah did indeed help him, when the Unbelievers drove him out: he had no more than one companion; they two were in the cave, and he said to his companion, "Have no fear, for Allah is with us": then Allah sent down His peace upon him, and strengthened him with forces which ye saw not, and humbled to the depths the word of the Unbelievers. But the word of Allah is exalted to the heights: for Allah is Exalted in might, Wise.

(135) Allah hath promised to Believers, men and women, gardens under which rivers flow, to dwell therein, and beautiful mansions in gardens of everlasting bliss. But the greatest bliss is the good pleasure of Allah: that is the supreme felicity.

(136) They swear by Allah that they said nothing (evil), but indeed they uttered blasphemy, and they did it after accepting Islam; and they meditated a plot which they were unable to carry out: this revenge of theirs was (their) only return for the bounty with which Allah and His Messenger had enriched them! If they repent, it will be best for them; but if they turn back (to their evil ways), Allah will punish them with a grievous penalty in this life and in the Hereafter: They shall have none on earth to protect or help them.

(137) Allah hath prepared for them gardens under which rivers flow, to dwell therein: that is the supreme felicity.

(138) The Arabs of the desert are the worst in Unbelief and hypocrisy, and most fitted to be in ignorance of the command which Allah hath sent down to His Messenger: But Allah is All-knowing, All-Wise.

(139) The vanguard (of Islam)- the first of those who forsook (their homes) and of those who gave them aid, and (also) those who follow them in (all) good deeds,- well-pleased is Allah with them, as are they with Him: for them hath He prepared gardens under which rivers flow, to dwell therein for ever: that is the supreme felicity.

(140) which then is best? - he that layeth his foundation on piety to Allah and His good pleasure? - or he that layeth his foundation on an undermined sand-cliff ready to crumble to pieces? and it doth crumble to pieces with him, into the fire of Hell. And Allah guideth not people that do wrong.