Deuteronomy 17:5-7

5then you shall bring that man or that woman who has done this evil thing to the gates [of your city] and you shall stone the man or the woman to death.

6On the evidence of two or three witnesses, he who is to die shall be put to death; he shall not be put to death on the evidence of [only] one witness.

7The hand of the witnesses shall be the first against him to put him to death, and afterward the hand of all the people. So you shall remove the evil from among you.