Muwatta Imam Malik Book of Divorce, Hadith 93
Yahya related to me from Malik that he had heard that Said ibn al-Musayyab and Sulayman ibn Yasar said, "The idda of a slave-girl when her husband dies is two months and five days."
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، وَسُلَيْمَانَ بْنَ يَسَارٍ، كَانَا يَقُولاَنِ عِدَّةُ الأَمَةِ إِذَا هَلَكَ عَنْهَا زَوْجُهَا شَهْرَانِ وَخَمْسُ لَيَالٍ .