Sahih al-Bukhari, Book 65, Hadith 4842 (In-Book) ⓘ
`Abdullah bin Al-Mughaffal Al-Muzani also said: "The Prophet also forbade urinating at the place where one takes a bath."
وَعَنْ عُقْبَةَ بْنِ صُهْبَانَ، قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ الْمُغَفَّلِ الْمُزَنِيِّ، فِي الْبَوْلِ فِي الْمُغْتَسَلِ.
also referenced under: Hadith 4842 (DarusSalam) & Volume 6, Book 60, Hadith 365 (USC-MSA)