Mishkat al-Masabih #1950

Umm al-Fadl daughter of al-Harith said that on the day of 'Arafa some people near her argued about whether God’s messenger was fasting, some saying that he was and others saying that he was not. She therefore sent him a cup of milk while he was observing the halt at ‘Arafa on his camel, and he drank it. (Bukhari and Muslim.)