It is narrated from Hazrat Abu Bakrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Fast upon sighting the moon and celebrate Eid upon sighting the moon. If on any day it is cloudy, then complete the count of thirty. And the month is sometimes like this and sometimes like this." The third time, the Prophet (peace and blessings be upon him) folded his finger.