The word(s) "once" appears 105 time(s) in 102 verse(s) in Quran in Mohsin Khan translation.

(81) So let not their speech, then, grieve you (O Muhammad صلى الله عليه وسلم). Verily, We know what they conceal and what they reveal.

(82) Surely the religion (i.e. the worship and the obedience) is for Allah only. And those who take Auliya' (protectors, helpers, lords, gods) besides Him (say): "We worship them only that they may bring us near to Allah." Verily Allah will judge between them concerning that wherein they differ. Truly, Allah guides not him who is a liar, and a disbeliever.

(83) Allah knows the fraud of the eyes, and all that the breasts conceal.

(84) To Him (Alone) is referred the knowledge of the Hour. No fruit comes out of its sheath, nor does a female conceive nor brings forth (young), except by His Knowledge. And on the Day when He will call unto them (polytheists) (saying): "Where are My (so-called) partners (whom you did invent)?" They will say: "We inform You that none of us bears witness to it (that they are Your partners)!"

(85) Verily they are in doubt concerning the Meeting with their Lord? (i.e. Resurrection after their death, and their return to their Lord). Verily! He it is Who is surrounding all things!

(86) And they divided not till after knowledge had come to them, through (selfish) transgression between themselves. And had it not been for a Word that went forth before from your Lord for an appointed term, the matter would have been settled between them. And verily, those who were made to inherit the Scripture [i.e. the Taurah (Torah) and the Injeel (Gospel)] after them (i.e. Jews and Christians) are in grave doubt concerning it (i.e. Allah's true religion - Islam or the Qur'an).

(87) And those who dispute concerning Allah (His religion of Islamic Monotheism with which Muhammad صلى الله عليه و سلم has been sent), after it has been accepted (by the people), of no use is their dispute before their Lord and on them is wrath, and for them will be a severe torment.

(88) Those who believe not therein seek to hasten it, while those who believe are fearful of it, and know that it is the very truth. Verily, those who dispute concerning the Hour are certainly in error far away.

(89) So whatever you have been given is but (a passing) enjoyment for this worldly life, but that which is with Allah (Paradise) is better and more lasting for those who believe (in the Oneness of Allah - Islamic Monotheism) and put their trust in their Lord (concerning all of their affairs).

(90) And he ['Îsa (Jesus), son of Maryam (Mary)] shall be a known sign for (the coming of) the Hour (Day of Resurrection) [i.e. 'Isa's (Jesus) descent on the earth]. Therefore have no doubt concerning it (i.e. the Day of Resurrection). And follow Me (Allah) (i.e. be obedient to Allah and do what He orders you to do, O mankind)! This is the Straight Path (of Islamic Monotheism, leading to Allah and to His Paradise).