Umayr, the freed slave of Umm al-Fadl, said: The people were in doubt about whether the Messenger of Allah (peace and blessings be upon him) was fasting on the day of Arafah. Sayyidah Umm al-Fadl (may Allah be pleased with her) said: "I will find this out for you." So she sent a bowl of milk to him (peace and blessings be upon him), and he (peace and blessings be upon him) drank from it.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21498