Musannaf Ibn Abi Shayba 10:857

Abu Bakr narrated to us, he said: Hafs narrated to us, from Hajjaj, from al-Hakam, from Miqsam, from Ibn Abbas, and from Salim, from Ibn al-Hanafiyyah; they both said: If four months have passed in the *ila* (oath of abstention), it is an irrevocable divorce (*taliqa ba'ina*). And she must observe a waiting period (*idda*) of three menstrual cycles (*quru'*).