Musannaf Ibn Abi Shayba 19:204

Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Abd al-A’la, from Abu Jamila, from Ali, who said: The Prophet, peace and blessings of Allah be upon him, was informed about a slave girl of theirs who had committed adultery. He sent me to her and said: "Go and establish the prescribed punishment (hadd) upon her." I went and found that she had not yet dried from her blood (i.e., she had just given birth). I said: "Have you finished?" I said: "I found that she had not yet dried from her blood." He said: "When she has dried from her blood, then flog her." Then the Messenger of Allah, peace and blessings of Allah be upon him, said: "And establish the prescribed punishments upon those whom your right hands possess."