Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 27
Narated By Abdullah ibn Mughaffal : The Apostle of Allah (pbuh) said: No one of you should make water in his bath and then wash himself there (after urination).
The version of Ahmad has: Then performs ablution there, for evil thoughts come from it.