The word(s) "proof" appears 8 time(s) in 8 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) And they say: "None shall enter Paradise unless he be a Jew or a Christian." Those are their (vain) desires. Say: "Produce your proof if ye are truthful."

(2) O ye who believe! Take not for friends unbelievers rather than believers: Do ye wish to offer Allah an open proof against yourselves?

(3) The people of the Book ask thee to cause a book to descend to them from heaven: Indeed they asked Moses for an even greater (miracle), for they said: "Show us Allah in public," but they were dazed for their presumption, with thunder and lightning. Yet they worshipped the calf even after clear signs had come to them; even so we forgave them; and gave Moses manifest proofs of authority.

(4) O mankind! verily there hath come to you a convincing proof from your Lord: For We have sent unto you a light (that is) manifest.

(5) "Now have come to you, from your Lord, proofs (to open your eyes): if any will see, it will be for (the good of) his own soul; if any will be blind, it will be to his own (harm): I am not (here) to watch over your doings."

(6) Or have they taken for worship (other) gods besides him? Say, "Bring your convincing proof: this is the Message of those with me and the Message of those before me." But most of them know not the Truth, and so turn away.

(7) And from each people shall We draw a witness, and We shall say: "Produce your proof": then shall they know that the Truth is in Allah (alone), and the (lies) which they invented will leave them in lurch.

(8) Or have they a ladder, by which they can (climb up to heaven and) listen (to its secrets)? Then let (such a) listener of theirs produce a manifest proof.