Abstract
This paper investigates the procedure for determining the new Hijri Month between Brunei, Indonesia, Malaysia, and Singapore. It endeavours to understand the reason for dissimilarity in terms of practice between these four nations in commencing Hijri Month of Ramadan, Shawal, and Zulhijjah despite sharing the same lunar crescent visibility criterion. This study is conducted through the examination of literature with regards to regulations of the lunar crescent visibility criterion between these countries. The study finds out that the determination of the Hijri months, particularly Ramadan, Shawal, and Zulhijjah, varies among Malaysia, Indonesia, Brunei, and Singapore despite their shared criteria for the rest of the lunar calendar. Brunei relies on moon sightings coordinated by the Chief Syar'ie Judge and various governmental departments, culminating in approval by the Sultan. Indonesia conducts a comprehensive Sidang Isbat conference involving numerous religious and scientific bodies, with the final decision made by the Ministry of Religious Affairs. Malaysia's process involves Department of Islamic Development Malaysia (JAKIM) and multiple expert panels, with the final announcement made by the Keeper of the Ruler's Seal after royal consent. Singapore employs purely astronomical calculations using Unofficial Meeting of Religious Affairs Ministers of Brunei, Indonesia, Malaysia and Singapore (MABIMS) criteria without moon sightings due to environmental constraints. These countries' methods reflect their unique institutional, cultural, and religious contexts. Factors influencing these differences include reference points for lunar calculations, the principles of Islamic jurisprudence, and public comprehension. Indonesia's diverse demographic and significant influence from Muhammadiyah and Nahdlatul Ulama groups lead to varied practices. Malaysia experiences minimal impact from smaller groups but historically had a notable discrepancy in Ramadan 1983. Brunei's unified adherence to the Shafi'i School of Thought ensures consistency in moon sighting practices. Singapore's reliance on calculations is driven by its inability to perform moon sightings due to light and industrial pollution. The study concludes that while MABIMS countries aim for a unified lunar crescent visibility criterion, practical implementations remain distinct, leading to potential differences in the start of important Hijri months. The need for a unified reference point and further discussions among MABIMS officials is highlighted to achieve consistent Hijri month determinations.