Sayyiduna Umar (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings of Allah be upon him) said: When the night comes from this side (the east) and the day departs from that side (the west), and the sun sets, then the time for breaking the fast has arrived.

Sayyiduna Abdullah bin Abi Awfa (may Allah be pleased with him) narrated that we were on a journey with the Messenger of Allah (peace and blessings be upon him) while fasting. The Prophet (peace and blessings be upon him) said to a companion (Sayyiduna Bilal), "Dismount and mix some sattu (barley drink) for me." He replied, "O Messenger of Allah, the sun is still up." The Prophet (peace and blessings be upon him) again said, "Dismount and mix some sattu for me." This time too, he replied, "O Messenger of Allah, the sun is still up." But your command was still the same: "Dismount and mix some sattu for me." So he dismounted and mixed the sattu. Then the Prophet (peace and blessings be upon him) pointed to one side and said, "When you see that the night has started from here, then the fasting person should break his fast."