Hadithcore
Sahih al-Bukhari, 224
sahih

Narrated Hudhaifa:

Once the Prophet (ﷺ) went to the dumps of some people and passed urine while standing. He then asked for water and so I brought it to him and he performed ablution.

حَدَّثَنَا آدَمُ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، قَالَ أَتَى النَّبِيُّ صلى الله عليه وسلم سُبَاطَةَ قَوْمٍ فَبَالَ قَائِمًا، ثُمَّ دَعَا بِمَاءٍ، فَجِئْتُهُ بِمَاءٍ فَتَوَضَّأَ‏.‏

References2 variants
In-Book Reference
Book 4, Hadith 90
USC-MSA web (English) reference
Vol. 1, Book 4, Hadith 224 (deprecated numbering scheme)