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كتاب الأطعمة
70  
Food, Meals
(51)
Chapter: To rinse the mouth after taking meals
(51)
باب الْمَضْمَضَةِ بَعْدَ الطَّعَامِ
Sahih al-Bukhari 5455

Narrated Suwaid:

We went out with Allah's Messenger (ﷺ) to Khaibar. and when we reached As-Sahba', which (Yahya says) is one day' journey from Khaibar, the Prophet (ﷺ) asked for food, and he was offered nothing but Sawiq which we chewed and ate. Then the Prophet (ﷺ) asked for water and rinsed his mouth, and we too, rinsed our mouths along with him. He then led us in the Maghrib prayer without performing ablution again.
قَالَ يَحْيَى سَمِعْتُ بُشَيْرًا، يَقُولُ حَدَّثَنَا سُوَيْدٌ، خَرَجْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم إِلَى خَيْبَرَ، فَلَمَّا كُنَّا بِالصَّهْبَاءِ ـ قَالَ يَحْيَى وَهْىَ مِنْ خَيْبَرَ عَلَى رَوْحَةٍ ـ دَعَا بِطَعَامٍ فَمَا أُتِيَ إِلاَّ بِسَوِيقٍ، فَلُكْنَاهُ فَأَكَلْنَا مَعَهُ، ثُمَّ دَعَا بِمَاءٍ فَمَضْمَضَ وَمَضْمَضْنَا مَعَهُ، ثُمَّ صَلَّى بِنَا الْمَغْرِبَ وَلَمْ يَتَوَضَّأْ‏.‏ وَقَالَ سُفْيَانُ كَأَنَّكَ تَسْمَعُهُ مِنْ يَحْيَى‏.‏
Reference : Sahih al-Bukhari 5455
In-book reference : Book 70, Hadith 84
USC-MSA web (English) reference : Vol. 7, Book 65, Hadith 365
  (deprecated numbering scheme)