Musnad Abu Ya'la al-Mawsili 73:2

Hadba ibn Khalid narrated to us, Hammam ibn Yahya narrated to us, Qatada narrated to us, from Sa'id ibn al-Musayyib, from 'Amir ibn Abi Umayya, the brother of Umm Salama, from Umm Salama, who said: The Messenger of Allah (may Allah bless him and grant him peace) would wake up in a state of janaba (major ritual impurity), and he would fast, and he would not break his fast.