Hadith 10:180
Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Sa’id, from Qatada, from al-Hasan—and it is the statement of Qatada—that they both said: If a man says to his wife, "Observe your waiting period (idda) three times," she is not lawful for him until she marries a husband other than him.
حدثنا أبو بكر قال نا عبد الأعلى عن سعيد عن قتادة عن الحسن وهو قول قتادة أنهما قالا إذا قال الرجل لأمرأته اعتدي ثلاثا لم تحل له حتى تنكح زوجا غيره