Musannaf Ibn Abi Shayba 13:1651

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Ibn Abi Khalid, from al-Sha’bi, he said: He was asked about a slave who secretly gave money to a man, so he bought him and then emancipated him. Al-Sha’bi said: "If I had caught him, I would have punished him with a severe punishment."