The word(s) "once" appears 177 time(s) in 167 verse(s) in Quran in Muhammad Pickthal translation.

(91) Lo! He knoweth that which is said openly, and that which ye conceal.

(92) Among mankind is he who disputeth concerning Allah without knowledge, and followeth each froward devil;

(93) O mankind! if ye are in doubt concerning the Resurrection, then lo! We have created you from dust, then from a drop of seed, then from a clot, then from a little lump of flesh shapely and shapeless, that We may make (it) clear for you. And We cause what We will to remain in the wombs for an appointed time, and afterward We bring you forth as infants, then (give you growth) that ye attain your full strength. And among you there is he who dieth (young), and among you there is he who is brought back to the most abject time of life, so that, after knowledge, he knoweth naught. And thou (Muhammad) seest the earth barren, but when We send down water thereon, it doth thrill and swell and put forth every lovely kind (of growth).

(94) And among mankind is he who disputeth concerning Allah without knowledge or guidance or a scripture giving light,

(95) These twain (the believers and the disbelievers) are two opponents who contend concerning their Lord. But as for those who disbelieve, garments of fire will be cut out for them; boiling fluid will be poured down on their heads,

(96) Allah will judge between you on the Day of Resurrection concerning that wherein ye used to differ.

(97) Lo! those who love that slander should be spread concerning those who believe, theirs will be a painful punishment in the world and the Hereafter. Allah knoweth. Ye know not.

(98) And those who disbelieve say: Why is the Qur'an not revealed unto him all at once? (It is revealed) thus that We may strengthen thy heart therewith; and We have arranged it in right order.

(99) Who created the heavens and the earth and all that is between them in six Days, then He mounted the Throne. The Beneficent! Ask anyone informed concerning Him!

(100) Say (O Muhammad, unto the disbelievers): My Lord would not concern Himself with you but for your prayer. But now ye have denied (the Truth), therefor there will be judgment.