Sayyiduna Ibn Umar (may Allah be pleased with them both) said: The people saw the moon (but it was not shown), I submitted to the Messenger of Allah (peace and blessings be upon him) that I have seen the moon, so he (peace be upon him) fasted and ordered the people to fast.
Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: A Bedouin came to the Prophet (peace and blessings be upon him) and said: I have seen the moon. The Prophet (peace and blessings be upon him) said: "Do you bear witness that there is no deity except Allah and that I am the Messenger of Allah?" He said: Yes. The Prophet (peace and blessings be upon him) said: "O Bilal! Announce among the people that they should fast tomorrow."