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."
Reference: Sahih al-Bukhari
USC-MSA web (English) : Vol. 6, Book 60, Hadith 365
Arabic : Book 65, Hadith 4842