Allah's Messenger (ﷺ) said, "The month (can be) 29 nights (i.e. days), and do not fast till you see the moon, and if the sky is overcast, then complete Sha'ban as thirty days."
Hadith Text
Allah's Messenger (ﷺ) said, "The month (can be) 29 nights (i.e. days), and do not fast till you see the moon, and if the sky is overcast, then complete Sha'ban as thirty days."
Reference: Sahih al-Bukhari 1907
Commentary on the Lunar Month
The Prophet (ﷺ) informs us that the lunar month may consist of either 29 or 30 days. This establishes the fundamental principle that Islamic months are determined by the lunar cycle, not fixed calculations. The variation between 29 and 30 days reflects the natural astronomical reality of the moon's orbit.
This teaching emphasizes that our worship must align with the actual sighting of the crescent moon, demonstrating submission to Allah's prescribed method for determining times of worship.
The Prohibition of Premature Fasting
"Do not fast till you see the moon" establishes a clear prohibition against beginning the Ramadan fast based on speculation or calculation alone. The physical sighting of the crescent moon is the primary means for determining the commencement of Ramadan.
This instruction protects the unity of the Muslim community by ensuring all begin fasting simultaneously based on verified sighting, preventing division that could occur through differing calculations.
The Ruling for Overcast Conditions
When clouds or weather conditions prevent moon sighting, the Prophet (ﷺ) commanded completing Sha'ban as thirty days. This provides a practical solution for uncertain situations while maintaining the principle of visual confirmation.
This ruling demonstrates the wisdom of Islamic law in providing clear guidance for circumstances where the primary method cannot be implemented, ensuring the preservation of both religious principles and communal harmony.
Legal Implications
This hadith forms the foundation for the Islamic legal methodology of moon sighting. Scholars have derived from it that Ramadan begins only with verified sighting of the crescent moon, or by completing thirty days of Sha'ban when sighting is impossible.
The specification of Sha'ban indicates that each month must be treated independently - we do not assume thirty days for Ramadan based on this ruling, but only for Sha'ban when the subsequent month's moon cannot be sighted.