Musnad Ahmad 33:591

Ishaq narrated to us, Fulayh ibn Sulayman al-Madani narrated to me, from Sa’id ibn al-Harith, from Jabir ibn Abdullah al-Ansari, that the Messenger of Allah (peace and blessings of Allah be upon him) came to some people of the Ansar to visit a sick person. He asked them for water to drink, and there was a water channel near him. He said: "If they have water that has spent the night in a waterskin, [we will drink it]; otherwise, we will drink directly from the channel."