Ibn Abbas reported: The Messenger of Allah, peace and blessings be upon him, drank some milk and rinsed his mouth. The Prophet said, “It contains fatty grease.”
Source: Ṣaḥīḥ al-Bukhārī 208, Ṣaḥīḥ Muslim 358
Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim
Al-Tirmidhi said, “Some of the scholars held the opinion that the mouth should be rinsed after drinking milk and according to us it is recommended. Some of them held the opinion that one does not need to rinse the mouth after drinking milk.”
Source: Sunan al-Tirmidhī 89
عَنْ ابْنِ عَبَّاسٍ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ شَرِبَ لَبَنًا فَمَضْمَضَ وَقَالَ إِنَّ لَهُ دَسَمًا
208 صحيح البخاري كتاب الوضوء باب هل يمضمض من اللبن
358 صحيح مسلم كتاب الحيض باب نسخ الوضوء مما مست النار
قال الترمذي قَدْ رَأَى بَعْضُ أَهْلِ الْعِلْمِ الْمَضْمَضَةَ مِنْ اللَّبَنِ وَهَذَا عِنْدَنَا عَلَى الِاسْتِحْبَابِ وَلَمْ يَرَ بَعْضُهُمْ الْمَضْمَضَةَ مِنْ اللَّبَنِ
89 سنن الترمذي كتاب الطهارة باب في المضمضة من اللبن