Purification (Kitab Al-Taharah)
Dawud :: Book 1 : Hadith 27
Narrated Abdullah ibn Mughaffal:
The Apostle of Allah (peace_be_upon_him) 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.