'Witnesses' in the Bible

On the evidence of two witnesses or three witnesses, he who is to die shall be put to death; he shall not be put to death on the evidence of one witness.

The hand of the witnesses shall be first against him to put him to death, and afterward the hand of all the people. So you shall purge the evil from your midst.

“A single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed.