Musannaf Ibn Abi Shaybah 30738 — Who begins the stoning?

Abd al-Rahman bin Abdullah bin Mas'ud said: Sayyiduna Ali (may Allah be pleased with him) said: O people! Zina (unlawful sexual intercourse) is of two kinds: secret zina and open zina. Secret zina is when witnesses testify to the zina, so the witnesses will be the first to throw stones, then the ruler, then the people. Open zina is when pregnancy becomes apparent or there is a confession, so the Imam will be the first to throw stones. The narrator said: He had three stones in his hand, and he threw one stone at the woman, and it struck the opening of her ear, and she began to spin around, and the people threw stones.