Sahih al-Bukhari Book 74, Hadith 31
Abu Humaid brought a cup of mix from a place called Al-Naqi. Allah's Messenger (ﷺ) said to him, "Will you
not cover it, even by placing a stick across its"
The people doubted whether Allah's Messenger (ﷺ) was fasting or the Day of `Arafat or not. So I sent a cup containing milk to him and he drank it.
Abu Humaid, an Ansari man, came from AnNaqi carrying a cup of milk to the Prophet. The Prophet (ﷺ) said, "Will you not cover it even by placing a stick across it?"