[Machine] The messenger of Allah ﷺ went to visit a group of people, and I happened to be standing nearby. I moved away from him but he said, "Come closer." So, I approached him and then he performed ablution and wiped over his leather socks, according to the authentic Hadith mentioned in Sahihain from the narration of Al-A'mash.  

قَامَ رَسُولُ اللهِ ﷺ إِلَى سُبَاطَةِ قَوْمٍ فَبَالَ قَائِمًا فَتَنَحَّيْتُ عَنْهُ فَقَالَ ادْنُهْ فَدَنَوْتُ ثُمَّ تَوَضَّأَ وَمَسَحَ عَلَى خُفَّيْهِ مُخَرَّجٌ فِي الصَّحِيحَيْنِ مِنْ حَدِيثِ الْأَعْمَشِ  

The Prophet ﷺ and I walked till we reached the dumps of some people. He stood, as any one of you stands, behind a wall and urinated. I went away, but he beckoned me to come. So I approached him and stood near his back till he finished. (Using translation from Bukhārī 225)   

لَقَدْ رَأَيْتُنِي أَنَا وَرَسُولُ اللهِ ﷺ نَتَمَاشَى فَأَتَى سُبَاطَةَ قَوْمٍ خَلْفَ الْحَائِطِ فَبَالَ كَمَا يَقُومُ أَحَدُكُمْ قَالَ فَانْتَبَذْتُ مِنْهُ فَأَشَارَ إِلِيَّ فَجِئْتُ فَقُمْتُ عِنْدَ عَقِبِهِ حَتَّى فَرَغَ  

[Machine] That the Messenger of Allah ﷺ came to a certain people called Subaita, and he became ill while standing. So, I met Mansur (a person) and asked him to tell me what Abu Wail narrated from Hudhaifah, that the Messenger of Allah ﷺ came to a certain people called Subaita, and he became ill while standing, like this.  

أَنَّ رَسُولَ اللهِ ﷺ أَتَى سُبَاطَةَ قَوْمٍ فَبَالَ قَائِمًا فَلَقِيتُ مَنْصُورًا فَسَأَلْتُهُ فَحَدَّثَنِيهِ عَنْ أَبِي وَائِلٍ عَنْ حُذَيْفَةَ أَنَّ رَسُولَ اللهِ ﷺ أَتَى سُبَاطَةَ قَوْمٍ فَبَالَ قَائِمًا كَذَا  

[Machine] It is said that the Prophet ﷺ urinated while standing with a wound on his foot. The imam, may Allah have mercy on him, said that it was previously known that the Arabs would use urine to treat a pain in the joints, so perhaps the Prophet did so at that time due to the pain in his foot. Ash-Shafi'i, may Allah have mercy on him, mentioned this incident in a similar manner. It is also said that the Prophet did so because he could not find a place or a spot to sit, and Allah knows best.  

أَنَّ النَّبِيَّ ﷺ بَالَ قَائِمًا مِنْ جُرْحٍ كَانَ بِمَأْبِضِهِ قَالَ الْإِمَامُ رَحِمَهُ اللهُ تَعَالَى وَقَدْ قِيلَ كَانَتِ الْعَرَبُ تَسْتَشْفِي لِوَجَعِ الصُّلْبِ بِالْبَوْلِ قَائِمًا فَلَعَلَّهُ كَانَ بِهِ إِذْ ذَاكَ وَجَعُ الصُّلْبِ وَقَدْ ذَكَرَهُ الشَّافِعِيُّ رَحِمَهُ اللهُ تَعَالَى بِمَعْنَاهُ وَقِيلَ إِنَّمَا فَعَلَ ذَلِكَ لِأَنَّهُ لَمْ يَجِدْ لِلْقُعُودِ مَكَانًا أَوْ مَوْضِعًا وَاللهُ أَعْلَمُ