Sahih Muslim 2029 b
Anas reported:
The Apostle of Allah (may peace he upon him) came to Medina when I was ten years old and he died when I was twenty years old. My mother exhorted me to serve him. He (the Holy Prophet) came to our house, and we ruined a flabby goat for him and mixed it (the milk) with water from the well of the house. Allah's Messenger (ﷺ) drank that. Umar and Abu Bakr on his left side said to him: Allah's Messenger, give it to Abu Bakr, but he (the Holy Prophet) gave it to the desert Arab who was on his right. Allah's Messenger (ﷺ) said: He who is on the right, then he who is on the right.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَعَمْرٌو النَّاقِدُ، وَزُهَيْرُ بْنُ حَرْبٍ، وَمُحَمَّدُ بْنُ عَبْدِ،
 اللَّهِ بْنِ نُمَيْرٍ - وَاللَّفْظُ لِزُهَيْرٍ - قَالُوا حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ أَنَسٍ، قَالَ
 قَدِمَ النَّبِيُّ صلى الله عليه وسلم الْمَدِينَةَ وَأَنَا ابْنُ عَشْرٍ وَمَاتَ وَأَنَا ابْنُ عِشْرِينَ وَكُنَّ أُمَّهَاتِي
 يَحْثُثْنَنِي عَلَى خِدْمَتِهِ فَدَخَلَ عَلَيْنَا دَارَنَا فَحَلَبْنَا لَهُ مِنْ شَاةٍ دَاجِنٍ وَشِيبَ لَهُ مِنْ بِئْرٍ فِي
 الدَّارِ فَشَرِبَ رَسُولُ اللَّهِ صلى الله عليه وسلم فَقَالَ لَهُ عُمَرُ وَأَبُو بَكْرٍ عَنْ شِمَالِهِ يَا رَسُولَ
 اللَّهِ أَعْطِ أَبَا بَكْرٍ ‏.‏ فَأَعْطَاهُ أَعْرَابِيًّا عَنْ يَمِينِهِ وَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم
 ‏
"‏ الأَيْمَنَ فَالأَيْمَنَ ‏"‏ ‏.‏