The word(s) "proof" appears 60 time(s) in 58 verse(s) in Quran in Muhammad Pickthal translation.

(41) And Korah, Pharaoh and Haman! Moses came unto them with clear proofs (of Allah's Sovereignty), but they were boastful in the land. And they were not winners (in the race).

(42) Have they not travelled in the land and seen the nature of the consequence for those who were before them? They were stronger than these in power, and they dug the earth and built upon it more than these have built. Messengers of their own came unto them with clear proofs (of Allah's Sovereignty). Surely Allah wronged them not, but they did wrong themselves.

(43) And if they deny thee, those before them also denied. Their messengers came unto them with clear proofs (of Allah's Sovereignty), and with the Psalms and the Scripture giving light.

(44) Say: Have ye seen your partner-gods to whom ye pray beside Allah? Show me what they created of the earth! Or have they any portion in the heavens? Or have We given them a scripture so they act on clear proof therefrom? Nay, the evil-doers promise one another only to deceive.

(45) And those who drive away (the wicked) with reproof

(46) That was because their messengers kept bringing them clear proofs (of Allah's Sovereignty) but they disbelieved; so Allah seized them. Lo! He is Strong, severe in punishment.

(47) And a believing man of Pharaoh's family, who hid his faith, said: Would ye kill a man because he saith: My Lord is Allah, and hath brought you clear proofs from your Lord? If he is lying, then his lie is upon him; and if he is truthful, then some of that wherewith he threateneth you will strike you. Lo! Allah guideth not one who is a prodigal, a liar.

(48) And verily Joseph brought you of old clear proofs, yet ye ceased not to be in doubt concerning what he brought you till, when he died, ye said: Allah will not send any messenger after him. Thus Allah deceiveth him who is a prodigal, a doubter.

(49) They say: Came not your messengers unto you with clear proofs? They say: Yea, verily. They say: Then do ye pray, although the prayer of disbelievers is in vain.

(50) Say (O Muhammad): I am forbidden to worship those unto whom ye cry beside Allah since there have come unto me clear proofs from my Lord, and I am commanded to surrender to the Lord of the Worlds.