Musannaf Ibn Abi Shayba 16:233

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Mansur, from Salim ibn Abi al-Ja’d, from his father, that Ibn Mas’ud invited a man to his food. The man said: "I have urinated." He (Ibn Mas’ud) said: "You have not urinated in your hand."