Anas said that the Prophet used to break his fast before praying with some fresh dates, but if there were no fresh dates he had a few dry dates, and if there were no dry dates he took some mouthfuls* of water.
*Mirqat explains this as three mouthfuls, but 'three' does not occur in the text.
Tirmidhi and Abu Dawud transmitted it, Tirmidhi saying that this is a hasan gharib tradition.