Muwatta Malik, Book 9, Hadith 84 (USC-MSA)

Yahya related to me from Malik from Amir ibn Abdullah ibn az- Zubayr from Amr ibn Sulaym az-Zuraqi from Abu Qutada al-Ansari that the Messenger of Allah, may Allah bless him and grant him peace, used to pray carrying Umama, who was the daughter of his daughter Zaynab by Abu'l As ibn Rabia ibn Abd Shams. When he prostrated, he put her down, and when he got up he carried her.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ عَامِرِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، عَنْ عَمْرِو بْنِ سُلَيْمٍ الزُّرَقِيِّ، عَنْ أَبِي قَتَادَةَ الأَنْصَارِيِّ، ‏.‏ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي وَهُوَ حَامِلٌ أُمَامَةَ بِنْتَ زَيْنَبَ بِنْتِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَلأَبِي الْعَاصِ بْنِ رَبِيعَةَ بْنِ عَبْدِ شَمْسٍ فَإِذَا سَجَدَ وَضَعَهَا وَإِذَا قَامَ حَمَلَهَا ‏.‏

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also referenced under: Book 9, Hadith 415 (In-Book)