"Whoever tells you that the Messenger of Allah ﷺ urinated standing up, do not believe him, for he would not urinate except while squatting." (Using translation from Nasāʾī 29)  

أَنَّ رَسُولَ اللهِ ﷺ بَالَ قَائِمًا فَلَا تُصَدِّقُوهُ مَا كَانَ يَبُولُ إِلَّا جَالِسًا»