The word(s) "must" appears 41 time(s) in 41 verse(s) in Quran in Abdullah Yusuf Ali translation.

(31) Behold! Thou didst say to one who had received the grace of Allah and thy favour: "Retain thou (in wedlock) thy wife, and fear Allah." But thou didst hide in thy heart that which Allah was about to make manifest: thou didst fear the people, but it is more fitting that thou shouldst fear Allah. Then when Zaid had dissolved (his marriage) with her, with the necessary (formality), We joined her in marriage to thee: in order that (in future) there may be no difficulty to the Believers in (the matter of) marriage with the wives of their adopted sons, when the latter have dissolved with the necessary (formality) (their marriage) with them. And Allah's command must be fulfilled.

(32) "But stop them, for they must be asked:

(33) And that Our forces,- they surely must conquer.

(34) Thou wilt see the Wrong-doers in fear on account of what they have earned, and (the burden of) that must (necessarily) fall on them. But those who believe and work righteous deeds will be in the luxuriant meads of the Gardens: they shall have, before their Lord, all that they wish for. That will indeed be the magnificent Bounty (of Allah).

(35) "And to our Lord, surely, must we turn back!"

(36) And verily Judgment and Justice must indeed come to pass.

(37) Allah has decreed: "It is I and My messengers who must prevail": For Allah is One full of strength, able to enforce His Will.

(38) Whereon the sky will be cleft asunder? His Promise needs must be accomplished.

(39) Assuredly, what ye are promised must come to pass.

(40) And hearkens to (the Command of) its Lord, and it must needs (do so);-