The word(s) "once" appears 119 time(s) in 116 verse(s) in Quran in Abdullah Yusuf Ali translation.

(71) "Allah will judge between you on the Day of Judgment concerning the matters in which ye differ."

(72) It is no fault on your part to enter houses not used for living in, which serve some (other) use for you: And Allah has knowledge of what ye reveal and what ye conceal.

(73) Such as fear not the meeting with Us (for Judgment) say: "Why are not the angels sent down to us, or (why) do we not see our Lord?" Indeed they have an arrogant conceit of themselves, and mighty is the insolence of their impiety!

(74) Those who reject Faith say: "Why is not the Qur'an revealed to him all at once? Thus (is it revealed), that We may strengthen thy heart thereby, and We have rehearsed it to thee in slow, well-arranged stages, gradually.

(75) Pharaoh said: "O Chiefs! no god do I know for you but myself: therefore, O Haman! light me a (kiln to bake bricks) out of clay, and build me a lofty palace, that I may mount up to the god of Moses: but as far as I am concerned, I think (Moses) is a liar!"

(76) And thy Lord knows all that their hearts conceal and all that they reveal.

(77) We (once) sent Noah to his people, and he tarried among them a thousand years less fifty: but the Deluge overwhelmed them while they (persisted in) sin.

(78) That (Allah) may question the (custodians) of Truth concerning the Truth they (were charged with): And He has prepared for the Unbelievers a grievous Penalty.

(79) Whether ye reveal anything or conceal it, verily Allah has full knowledge of all things.

(80) Men ask thee concerning the Hour: Say, "The knowledge thereof is with Allah (alone)": and what will make thee understand?- perchance the Hour is nigh!