Sahih al-Bukhari 5604

It is related from 'Umayr, the client of Umm al-Fadl, that Umm al-Fadl said, "The people were unsure about whether the Messenger of Allah, may Allah bless him and grant him peace, was fasting on the Day of 'Arafa, so I sent him a vessel containing milk and he drank." Sufyan [one of the transmitters] might have said, "The people were unsure about whether the Messenger of Allah, may Allah bless him and grant him peace, was fasting on the Day of 'Arafa, so Umm al-Fadl sent to him..." When he was asked about it [i.e. whether it is mursal or directly connected), he said, "It is from Umm al-Fadl."