Musnad Ahmad 473:1

Sufyan narrated to us, from ‘Amr, who said: Abu al-Minhal informed me, having heard Iyas ibn ‘Abd al-Muzani—and he was one of the companions of the Prophet, may God bless him and grant him peace—say: "Do not sell water, for I heard the Messenger of God, may God bless him and grant him peace, forbidding the sale of water." ‘Amr did not know which water it was.