I came to Messenger of Allah ﷺ with a cup of milk from Naqi' which had no cover over it, whereupon he said: Why did you not cover it? - even if you had covered it only with a stick. Abu Humaid said that he had been ordered that waterskins be tied during the night, and the doors be closed during the night.  

أَتَيْتُ النَّبِيَّ ﷺ بِقَدَحِ لَبَنٍ مِنَ النَّقِيعِ لَيْسَ مُخَمَّرًا فَقَالَ أَلاَّ خَمَّرْتَهُ وَلَوْ تَعْرُضُ عَلَيْهِ عُودًا قَالَ أَبُو حُمَيْدٍ إِنَّمَا أُمِرَ بِالأَسْقِيَةِ أَنْ تُوكَأَ لَيْلاً وَبِالأَبْوَابِ أَنْ تُغْلَقَ لَيْلاً  

Abu Humaid Sa'idi reported through another chain of transmitters that he brought to Messenger of Allah ﷺ a cup containing milk, but there is no mention of the word" in the night  

أَنَّهُ أَتَى النَّبِيَّ ﷺ بِقَدَحِ لَبَنٍ بِمِثْلِهِ قَالَ وَلَمْ يَذْكُرْ زَكَرِيَّاءُ قَوْلَ أَبِي حُمَيْدٍ بِاللَّيْلِ  

We were with Messenger of Allah ﷺ and he asked for water. A person said: Messenger of Allah, may we not give you Nabidh to drink? He (the Holy Prophet) said: Yes (you may). He (the narrator) said: Then that person went out speedily and brought a cup containing Nabidh, whereupon Messenger of Allah ﷺ said: Why did you not cover it? - even if it is with a wood. He said that then he drank it.  

كُنَّا مَعَ رَسُولِ اللَّهِ ﷺ فَاسْتَسْقَى فَقَالَ رَجُلٌ يَا رَسُولَ اللَّهِ أَلاَ نَسْقِيكَ نَبِيذًا فَقَالَ بَلَى قَالَ فَخَرَجَ الرَّجُلُ يَسْعَى فَجَاءَ بِقَدَحٍ فِيهِ نَبِيذٌ فَقَالَ رَسُولُ اللَّهِ ﷺ أَلاَّ خَمَّرْتَهُ وَلَوْ تَعْرُضُ عَلَيْهِ عُودًا قَالَ فَشَرِبَ  

Why did you not cover it even with a wood across it?  

يُقَالُ لَهُ أَبُو حُمَيْدٍ بِقَدَحٍ مِنْ لَبَنٍ مِنَ النَّقِيعِ فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ أَلاَّ خَمَّرْتَهُ وَلَوْ تَعْرُضُ عَلَيْهِ عُودًا