Mukhtasar Sahih Bukhari — Hadith 1938

Jabir bin Abdullah (may Allah be pleased with him) narrates that Abu Humayd Ansari brought milk to the Prophet (peace be upon him) in a bowl from the place of Naqi’. The Messenger of Allah (peace be upon him) said to him: “Why did you not cover it? (At least) you could have placed a broad wooden board over it.”