Deuteronomy 17:4-6

Amplified Bible

⁴ and if it is told to you and you hear about it, then you shall investigate thoroughly [all the charges]. If it is confirmed ^[a]beyond doubt that this detestable thing has been done in Israel, ⁵ then 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. ^6 [b]On 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.