It is narrated from Ata' bin Abi Rabah (may Allah have mercy on him) that Mariyah (may Allah be pleased with her) observed an 'iddah of three menstrual periods after the Prophet (peace and blessings be upon him), meaning the mother of Ibrahim (may Allah be pleased with him). This is munqati' (broken), Suwayd bin Abd al-Aziz (may Allah have mercy on him) is a da'if (weak) narrator, and the narration of the group from Ata' (may Allah have mercy on him) is that this was his own view (madhhab).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15584