The Statement of Allah the Most High: "...When they gave their Bai'a (pledge) to you (O Muḥammad pbuh) under the tree..." (V.48:18)
وَعَنْ عُقْبَةَ بْنِ صُهْبَانَ، قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ الْمُغَفَّلِ الْمُزَنِيِّ، فِي الْبَوْلِ فِي الْمُغْتَسَلِ.
`Abdullah bin Al-Mughaffal Al-Muzani also said: "The Prophet (ﷺ) also forbade urinating at the place where one takes a bath."