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

(11) And Satan will say when the matter is decided: "It was Allah Who gave you a promise of Truth: I too promised, but I failed in my promise to you. I had no authority over you except to call you but ye listened to me: then reproach not me, but reproach your own souls. I cannot listen to your cries, nor can ye listen to mine. I reject your former act in associating me with Allah. For wrong-doers there must be a grievous penalty."

(12) He said: "There are my daughters (to marry), if ye must act (so)."

(13) (They must be raised up), in order that He may manifest to them the truth of that wherein they differ, and that the rejecters of Truth may realise that they had indeed (surrendered to) Falsehood.

(14) What is with you must vanish: what is with Allah will endure. And We will certainly bestow, on those who patiently persevere, their reward according to the best of their actions.

(15) Gardens of Eternity, those which (Allah) Most Gracious has promised to His servants in the Unseen: for His promise must (necessarily) come to pass.

(16) Not one of you but will pass over it: this is, with thy Lord, a Decree which must be accomplished.

(17) Not one of the beings in the heavens and the earth but must come to (Allah) Most Gracious as a servant.

(18) Moses said to him: Woe to you! Forge not ye a lie against Allah, lest He destroy you (at once) utterly by chastisement: the forger must suffer frustration!"

(19) (Pharaoh) said: "Believe ye in Him before I give you permission? Surely this must be your leader, who has taught you magic! be sure I will cut off your hands and feet on opposite sides, and I will have you crucified on trunks of palm-trees: so shall ye know for certain, which of us can give the more severe and the more lasting punishment!"

(20) Had it not been for a Word that went forth before from thy Lord, (their punishment) must necessarily have come; but there is a Term appointed (for respite).