Musannaf Ibn Abi Shayba 19:780

Abu Bakr narrated to us, he said: Hushaym narrated to us, from Mughira, from al-Sha'bi, that he was asked about a man who divorced his wife three times, then she brought forth a pregnancy from him, and he denied it. He (al-Sha'bi) said: He shall perform li'an (imprecation). Al-Harith said: "O Abu 'Amr, Allah said in His Book: 'And those who accuse their wives...' (24:6). Do you consider her his wife?" He (al-Sha'bi) said: "Yes." Then al-Sha'bi said: "I am indeed ashamed when I see the truth not to return to it."