Musannaf Ibn Abi Shaybah

Hazrat Ikrimah narrates that a Bedouin gave testimony of sighting the (Ramadan) moon before the Prophet (peace and blessings be upon him). The Prophet asked him, "Do you testify that there is no god but Allah and that I am the Messenger of Allah?" He replied, "Yes." The Prophet (peace and blessings be upon him) then ordered the people to begin fasting.

Hazrat Ibn Abi Laila narrates that Hazrat Umar bin Khattab accepted the testimony of a man regarding the moon.

Hazrat Abdul Malik bin Maisarah narrates that I saw the moon of Ramadan or Shawwal in Madinah. Only one person testified about the moon, so Hazrat Ibn Umar (may Allah be pleased with them) ordered that his testimony be accepted.

Hazrat Ibn Abbas (may Allah be pleased with them) narrates that once a Bedouin came to the presence of the Prophet (peace and blessings be upon him) and said that he had seen the moon the previous night. The Prophet asked him, "Do you bear witness that there is no god but Allah and that Muhammad is Allah's servant and His Messenger?" He replied, "Yes." The Prophet (peace and blessings be upon him) said, "O Bilal, announce among the people that they should fast tomorrow."