Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that I heard the Messenger of Allah (peace and blessings be upon him) say: "When you see the moon, then begin fasting, and when you see the moon, then break the fast, and if it is cloudy for you, then complete the counting."

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, Allah Almighty has made the moon a means for determining the times. Therefore, when you see it, begin fasting, and when you see it (again), stop fasting. But if clouds cover you (and you cannot see the moon), then complete the count (of days), and know well that the month does not exceed thirty days."

Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) said: "The month can also be of twenty-nine nights. Therefore, do not fast without sighting the moon, nor break the fast without sighting the moon, except if clouds cover you. Then, if it is cloudy, estimate and count the days of the month." Imam Abu Bakr (may Allah have mercy on him) says that Ismail bin Ja'far was one of the greatest hadith memorisers of his time in the world.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Messenger of Allah (peace and blessings of Allah be upon him) in the same manner as Sayyiduna Ibn Umar (may Allah be pleased with them both). The Prophet (peace and blessings of Allah be upon him) said: "Then if clouds cover you, count (the month of Sha'ban as) thirty days."

Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) said: "A month is like this, like this, and like this—thirty days. And a month is also like this and like this." And on the third (time), he folded his thumb (meaning, the month can also be twenty-nine days). "And if clouds cover you, then complete thirty days (of Sha'ban)." In the narration of Ibn Fudayl, it is mentioned: "Then the Prophet (peace and blessings be upon him) opened his hand and folded one finger (indicating twenty-nine). Then if clouds cover you, complete thirty days (of Sha'ban)."

It is narrated from Sayyidah Aisha (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) used to pay more attention to the crescent of Sha'ban than to the crescent of any other month. Then, upon sighting the crescent of Ramadan, he would fast. And if it was cloudy for him, he (peace and blessings be upon him) would count thirty days of Sha'ban and then fast.

Sayyiduna Hudhayfah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Do not proceed beyond this month (Ramadan) until you see the moon or complete the counting (of Sha'ban)."

Hazrat Simak narrates that I came to Sayyiduna Ikrimah on the day when there was doubt about the beginning of Ramadan, while he was eating food. So he said, "Come closer and eat food." I said, "I am fasting." He said, "By Allah, you will certainly come closer (and eat)." I said, "Then please explain this to me." He said, "Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated to us that the Messenger of Allah (peace and blessings be upon him) said: 'Do not welcome Ramadan (by fasting) before it. Fast when you see the moon and break your fast when you see the moon. Then if clouds or mist come between you and the sighting of the moon, then complete the counting (of Sha'ban) to thirty days.'"