Musnad Ahmad 1158:2

Bahz narrated to us, he said: Hammam narrated to us, from Qatadah, from Abu Ayyub, from Juwayriyah bint al-Harith, that the Prophet, peace and blessings of Allah be upon him, entered upon her on a Friday while she was fasting. He said: "Did you fast yesterday?" She said: "No." He said: "Do you intend to fast tomorrow?" She said: "No." He said: "Then break your fast."