Kurayb, the freed slave of Ibn Abbas (may Allah be pleased with them both), narrates from Umm Hani (may Allah be pleased with her) that on the day of the Conquest of Makkah the Messenger of Allah (peace and blessings be upon him) offered eight rak'ahs of the Duha prayer; he (peace and blessings be upon him) would say the salam after every two rak'ahs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4905