Hazrat Abdur Rahman bin Abi Laila narrates that when witnesses would testify to adultery before Hazrat Ali (may Allah be pleased with him), he would order the witnesses to throw stones first, then he would throw stones, then the people would throw stones. And when there was a confession, he himself would begin, so he would throw stones, then the people would throw stones.

Hazrat Abdur Rahman bin Abdullah bin Masood narrates that Hazrat Ali (may Allah be pleased with him) said: O people, indeed adultery is of two kinds: hidden adultery and open adultery. As for hidden adultery, it is when witnesses testify to the act of adultery, so the witnesses will be the first to throw stones, then the ruler, then the people. And open adultery is when pregnancy becomes apparent or there is a confession, so the Imam will be the first to throw a stone. The narrator says that there were some stones in your hand, so you threw a stone at that woman which struck her in the hole of her ear, so she started turning around and the people threw stones.

The aforementioned statement of Hazrat Ali (may Allah be pleased with him) is also transmitted with this chain from Hazrat Abdur Rahman in exactly the same wording.

Hazrat Amr bin Nafi’ narrates that Hazrat Ali (may Allah be pleased with him) said: There are two types of stoning (rajm): one is that in which the ruler throws stones first, then the people; and the other is that in which the witnesses throw stones first, then the ruler, then the people. The narrator says: I asked Hazrat Hakam,“What is the stoning by the Imam?”He replied: When the woman gives birth to a child or she confesses. And the stoning by the witnesses is when they give testimony.

30741 - So I said to Al-Hakam: When does the Imam stone? He said: When she gives birth or confesses, and the witnesses are stoned if they testify.

Hazrat Sha’bah says that I asked Hazrat Hakam,“What does it mean for a ruler to carry out rajm (stoning)?”He replied: When a woman gives birth to a child or confesses, and when witnesses give testimony, then the witnesses will begin (the stoning).