وَعَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ قَالَ: نَهَى رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنِ اخْتِنَاثِ الْأَسْقِيَةِ. زَادَ فِي رِوَايَةٍ: وَاخْتِنَاثُهَا: أَنْ يُقْلَبَ رَأْسُهَا ثُمَّ يُشْرَبَ مِنْهُ

Abu Sa'id al-Khudri said God’s messenger forbade the ikhtibath of water-skins, adding in a version that this means having their heads inverted and then being drunk from. (Bukhari and Muslim.)