Abu Dawud Book 20, Hadith Number 3715.

Chapter : Sipping water with the mouth.

Narated By Jabir b. ‘Abd Allah : The Prophet (may peace be upon him) went to visit a man of the Ansar accompanied by one of his Companions who was watering his garden. The Apostle of Allah (may peace be upon him) said: If you have any water which has remained over night in a skin (we should like it), or we shall sip. (from a streamlet).