Musnad Ahmad 30:1432

'Affan narrated to us, Wuhayb narrated to us, Khuthaym—meaning Ibn 'Arak—narrated to us, from his father, that Abu Hurayrah arrived in Medina with a group of his people while the Prophet, peace and blessings of Allah be upon him, was at Khaybar, and he had appointed Siba' ibn 'Urfutah as his deputy over Medina. He said: "I reached him while he was reciting in the morning prayer, in the first rak'ah, 'Kaf-Ha-Ya-'Ayn-Sad,' and in the second, 'Woe to those who give less [than due].'" He said: "I said to myself, 'Woe to so-and-so; when he measures for himself, he measures with the full amount, and when he measures for others, he measures with a deficiency.'" He said: "When he finished the prayer, he provided us with supplies until we reached Khaybar, and the Prophet, peace and blessings of Allah be upon him, had already conquered Khaybar." He said: "He spoke to the Muslims, and they included us in their shares."