Deuteronomy 17:2, 6, 7
Deuteronomy 17:2 NIV
If a man or woman living among you in one of the towns the LORD gives you is found doing evil in the eyes of the LORD your God in violation of his covenant
Deuteronomy 17:6 NIV
On the testimony of two or three witnesses a person is to be put to death, but no one is to be put to death on the testimony of only one witness.