Muslims in the Middle East ended their fasting for the holy month of Ramadan in disagreement, with some starting Eid Al-Fitr celebrations on Sunday while others waited until Monday to break their fast in what has become a particularly acrimonious dispute.Why It MattersThe row over when to end the fast — which is decided by the sighting of the moon and astronomical calculations — has highlighted division between different Muslim countries and their clerics and has added another dimension to the Middle East's many disputes.What To KnowOn Saturday, Saudi Arabia, the United Arab Emirates and Palestinian authorities announced the end of the holy month for Muslims so they could begin Eid Al-Fitr celebrations on Sunday, along with Qatar, Kuwait, Bahrain, Lebanon, Yemen, Turkey and Sudan.In contrast, Iran, Egypt, Syria, Jordan, Iraq, Oman observed Sunday as the last day of Ramadan. Algeria, Tunisia, Morrocco, Pakistan, Malaysia, and Indonesia also celebrated Eid on Monday.While slight disparities have been common in the past, the major difference sparked fury among Arab Muslims on social media, sarcasm and confusion for travelers."It is not reasonable or logical for some people to fast and others to break their fast in a contiguous geographical area! Syria fasts and Lebanon breaks its fast, Jordan fasts and Saudi Arabia breaks its fast," one Lebanese user posted on X.Each country's religious authorities determine the end of each Islamic month based on astronomical calculations and the sighting of the moon.Efforts to unify moon observation have been ongoing for decades to promote unity in observances and minimize disputes over the calendar.In Egypt, there was widespread disappointment."Happy Eid to you all. Eid has been postponed to Monday, and we demand the implementation of VAR," an Egyptian Facebook user posted in a humorous nod with a reference to the controversial video assistant referee that is used to doublecheck refereeing decisions in soccer matches.When does Ramadan end?Comments from Egyptian and Saudi social media users further highlighted religious and political rivalry between two Sunni leading countries in the region.Tensions also grew between Iraq's Sunni institutions over conflicting announcements, with dozens of Iraqis performing Eid prayers on Sunday, outside mosques and without clergy, according to media reports.This year's Ramadan has been marked by another public dispute between Sunnis and Shiites, and among Sunnis, over a Saudi TV series penned by an Egyptian journalist, delving into historical events that led to the ongoing Sunni-Shiite divide.One specific date must be the same for all the Muslim's roughly two-billion population: the Day of Arafah, when millions of pilgrims gather in Mecca, Saudi Arabia, to commemorate the final sermon of Prophet Muhammad. This year, it will be in early June.What People Are SayingSaudi King Salman bin Abdulaziz's official X account, on Sunday: "I congratulate you on the blessed Eid al-Fitr, after God Almighty has honored us with the fasting and prayers of the month of Ramadan. On this Eid, we ask God to perpetuate the security, stability and prosperity of our country, and to spread security and peace throughout our Islamic nation and the entire world."Egypt's Islamic institution, Dar al-Ifta: "Following some of the controversy raised regarding the determination of the beginning of Eid al-Fitr for this year, we would like to clarify the legal position clearly. The Egyptian Dar al-Ifta affirms that it follows a clear methodology that combines the established religious texts with reliance on precise astronomical calculations, which have reached the level of scientific certainty."What Happens NextAs Muslim countries must align calendars for June's Hajj season, more sectarian and political rifts could threaten regional stability.