رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 767
The Book About the Etiquette of Eating
Permission to Drink While Standing
وَعَنْ النزال بْن سبرة رضى اللَّه عَنْهُ قَالَ: أتى عَلِيٌّ رضى اللَّه عَنْهُ باب الرَّحَبَةِ فَشَرِبَ قَائِمًا، وَقَالَ: إِنِّي رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَعَلَ كَمَا رَأَيْتُمُونِي فَعَلْتُ.((رَوَاهُ البخارى))
An-Nazzal bin Sabrah (May Allah be pleased with him) reported: 'Ali bin Abu Talib (May Allah be pleased with him) arrived at Bab Ar-Rahbah (in Kufah) and drank water in a standing posture. Then he said: "I saw the Messenger of Allah (ﷺ) doing what you have seen me doing." [Al-Bukhari].
Riyad as-Salihin, 767