The Book of Fasting - Sunan an-Nasa'i 2120

I heard the messenger of Allah say: 'When you see the crescent then fast, and when you see it, then stop fasting, and if it is obscured from you (too cloudy), then work it out (for the beginning of the month, to complete thirty days)'

Commentary on the Lunar Sighting

This noble hadith establishes the fundamental principle for determining the beginning and end of Ramadan through physical sighting of the crescent moon. The Prophet (peace be upon him) emphasized direct visual observation as the primary method, reflecting the simplicity and practicality of Islamic legislation.

The command "when you see the crescent then fast" indicates that fasting becomes obligatory upon confirmed sighting, regardless of astronomical calculations. This approach maintains the unity of the Muslim community under a single visible sign accessible to all people, regardless of their scientific knowledge.

The Cloudy Night Provision

The phrase "if it is obscured from you" addresses the situation where cloud cover prevents moon sighting. In such cases, the instruction "then work it out" means to complete thirty days of the previous month (Sha'ban). This ensures the month of Ramadan maintains its proper length and prevents uncertainty in worship.

Scholars explain that "working it out" refers to completing thirty days of Sha'ban before commencing Ramadan, and similarly completing thirty days of fasting before celebrating Eid al-Fitr. This method preserves the lunar nature of the Islamic calendar while providing a clear solution for exceptional circumstances.

Legal Implications and Scholarly Consensus

The majority of scholars understand this hadith as requiring actual sighting of the crescent moon by trustworthy witnesses. The repetition of "when you see it" emphasizes the importance of visual confirmation over theoretical calculation.

This teaching establishes that the start and end of Ramadan are matters of religious observance (ta'abbudi) rather than astronomical science alone. The wisdom behind this approach includes maintaining the distinctive character of Islamic worship and ensuring universal applicability across different regions and educational backgrounds.