Witness: Required to Throw the First Stone in Executing the Sentence
Source: Nav
Deuteronomy 13:9
Instead, you must surely kill him. Your hand must be the first against him to put him to death, and then the hands of all the people.
Deuteronomy 17:5–7
you must bring out to your gates the man or woman who has done this evil thing, and you must stone that person to death. / On the testimony of two or three witnesses a man shall be put to death, but he shall not be executed on the testimony of a lone witness. / The hands of the witnesses shall be the first in putting him to death, and after that, the hands of all the people. So you must purge the evil from among you.
Acts 7:58
They dragged him out of the city and began to stone him. Meanwhile the witnesses laid their garments at the feet of a young man named Saul.