The word(s) "witness" appears 111 time(s) in 90 verse(s) in Quran in Muhammad Pickthal translation.

(11) When Allah made (His) covenant with the prophets, (He said): Behold that which I have given you of the Scripture and knowledge. And afterward there will come unto you a messenger, confirming that which ye possess. Ye shall believe in him and ye shall help him. He said: Do ye agree, and will ye take up My burden (which I lay upon you) in this (matter)? They answered: We agree. He said: Then bear ye witness. I will be a witness with you.

(12) How shall Allah guide a people who disbelieved after their belief and (after) they bore witness that the messenger is true and after clear proofs (of Allah's Sovereignty) had come unto them. And Allah guideth not wrongdoing folk.

(13) Say: O People of the Scripture! Why disbelieve ye in the revelations of Allah, when Allah (Himself) is witness of what ye do?

(14) Say: O People of the Scripture! Why drive ye back believers from the way of Allah, seeking to make it crooked, when ye are witnesses (to Allah's guidance)? Allah is not unaware of what ye do.

(15) If ye have received a blow, the (disbelieving) people have received a blow the like thereof. These are (only) the vicissitudes which We cause to follow one another for mankind, to the end that Allah may know those who believe and may choose witnesses from among you; and Allah loveth not wrong-doers.

(16) Prove orphans till they reach the marriageable age; then, if ye find them of sound judgment, deliver over unto them their fortune; and devour it not by squandering and in haste lest they should grow up Whoso (of the guardians) is rich, let him abstain generously (from taking of the property of orphans); and whoso is poor let him take thereof in reason (for his guardianship). And when ye deliver up their fortune unto orphans, have (the transaction) witnessed in their presence. Allah sufficeth as a Reckoner.

(17) As for those of your women who are guilty of lewdness, call to witness four of you against them. And if they testify (to the truth of the allegation) then confine them to the houses until death take them or (until) Allah appoint for them a way (through new legislation).

(18) And unto each We have appointed heirs of that which parents and near kindred leave; and as for those with whom your right hands have made a covenant, give them their due. Lo! Allah is ever witness over all things.

(19) But how (will it be with them) when We bring of every people a witness, and We bring thee (O Muhammad) a witness against these?

(20) Whatever of good befalleth thee (O man) it is from Allah, and whatever of ill befalleth thee it is from thyself. We have sent thee (Muhammad) as a messenger unto mankind and Allah is sufficient as witness.