سنن النسائي 38

It was narrated from Al-Muhajir bin Qunfudh that he greeted the Prophet (ﷺ) with Salam while he was urinating, and he did not return the greeting until he had performed Wudu'. When he had performed Wudu' he returned the greeting

Rapporté par Al-Muhajir bin Qunfudh : Il a salué le Prophète (ﷺ) alors qu’il urinait, et il n’a pas répondu à son salut avant d’avoir fait ses ablutions. Une fois les ablutions faites, il lui a rendu le salut