Hadith 56

Sahih Bukhari

Book 4: Ablutions (Wudu')

Chapter 40

The using of the remaining water after ablution

باب اسْتِعْمَالِ فَضْلِ وَضُوءِ النَّاسِ

And Jarir bin ‘Abdullah ordered the members of his family to perform ablution with the water in which he had put his Siwak (a piece of a root of a tree called Al-Arak used as a toothbrush). ​​
وَأَمَرَ جَرِيرُ بْنُ عَبْدِ اللَّهِ أَهْلَهُ أَنْ يَتَوَضَّئُوا بِفَضْلِ سِوَاكِهِ.
Sahih al-Bukhari 190
حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ يُونُسَ، قَالَ حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنِ الْجَعْدِ، قَالَ سَمِعْتُ السَّائِبَ بْنَ يَزِيدَ، يَقُولُ ذَهَبَتْ بِي خَالَتِي إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَتْ يَا رَسُولَ اللَّهِ، إِنَّ ابْنَ أُخْتِي وَجِعٌ‏.‏ فَمَسَحَ رَأْسِي وَدَعَا لِي بِالْبَرَكَةِ، ثُمَّ تَوَضَّأَ فَشَرِبْتُ مِنْ وَضُوئِهِ، ثُمَّ قُمْتُ خَلْفَ ظَهْرِهِ، فَنَظَرْتُ إِلَى خَاتَمِ النُّبُوَّةِ بَيْنَ كَتِفَيْهِ مِثْلِ زِرِّ الْحَجَلَةِ‏.‏
As-Sa'ib bin Yazid:

My aunt took me to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! This son of my sister has got a disease in his legs." So he passed his hands on my head and prayed for Allah's blessings for me; then he performed ablution and I drank from the remaining water. I stood behind him and saw the seal of Prophethood between his shoulders, and it was like the "Zir-al-Hijla" (means the button of a small tent, but some said 'egg of a partridge.' etc.)