Nearly 2.5 million Muslims gathered at the sacred hill of Mount Arafat at dawn on Saturday for what is considered the climax of the Hajj pilgrimage. Many had tears streaming down their faces as they weaved their way towards the rocky outcrop where Prophet Muhammad delivered his final sermon about 1,400 years ago. As one of the largest religious gatherings on earth, the second day of Hajj on Mount Arafat, or hill of mercy, is often the most memorable for pilgrims. Worshippers stand shoulder to shoulder with Muslims from around the world, seeking mercy, blessings and good health. "Really, I am very satisfied," said Lassina Coulibaly, 47, as pilgrims clutching brightly coloured umbrellas gathered under the blazing sun. "Fatigue is part of the pilgrimage," said the father-of-seven. "I came last year during Ramadan, now I am there for the Hajj," said Indonesian pilgrim Zakir Uddin, 27. "It is an honour, praise be to God.” This year, more than 1.8 million people from more than 160 countries travelled to Saudi Arabia to perform the Hajj, according to Saudi officials. Some 20,000 were US citizens and residents, while a further 200,000 pilgrims were from Saudi. The five-day Hajj pilgrimage is required of all Muslims once in their lifetime, if they are financially and physically able to make the demanding journey. Due to the Islamic calendar being based on a lunar cycle, the time of year when it takes place varies, with temperatures soaring to more than 38C during the hot summer months. This year, unusually, worshippers not only had to contend with fierce sunshine but also had to endure strong winds and outbreaks of heavy rain. Many pilgrims save money for years if not decades to be able to afford completing the Hajj. The journey takes them to Islam's holiest sites to perform a series of ancient rituals, all the while following a route the Prophet Muhammad once walked. According to Saudi Arabia's state-run media, the oldest pilgrim this year was 103-year-old Noah Lanai from Thailand. The woman came to the Hajj with her son and was quoted as saying she had long dreamed of praying in Makkah. Muslims believe the Hajj is a chance to atone and an opportunity to erase past sins. It is also a chance to pray for unity and peace. "I wish the best for all people, and hope Syria will return to normal and hope all people will be good," said Syrian pilgrim Ahmad Wahid as he ascended Mount Arafat for prayer and worship. Thousands of faithful spent the night under the stars by the hillside, sleeping on prayer rugs or pieces of cardboard. Trucks were also parked at regular intervals on the route leading up to the hill, distributing bottles of water and meals to the faithful. Meanwhile, thousands more workers prepared to clear up the rubbish that littered the ground. During the Hajj, male pilgrims wear simple, white cloth garments, while women forgo makeup and perfume and wear loose-fitting clothing and a head covering. This state of "ihram," or spiritual purity, is intended for pilgrims to focus on the inner self over their outward appearance. The white garments worn by men are forbidden to contain any stitching - a restriction meant to emphasise the equality of all Muslims and prevent wealthier pilgrims from differentiating themselves with more elaborate garments. After spending the day in prayer on Mount Arafat, the pilgrims headed towards an area called Muzdalifa, about 9 kilometres to the west. Many walked, while others took buses. In Muzdalifa, followers pick up pebbles that will be used for a symbolic stoning of the devil and casting away of evil. This takes place over three days in Mina, an area about 20km east of Makkah. The final days of Hajj coincide with Eid al-Adha, or the festival of sacrifice, which honours Ibrahim’s willingness to kill his son as an act of obedience to God. "This is my fifth time volunteering on Hajj," Ayman Al Khalwai, a volunteer first aid instructor with the Civil Defence told <em>The National</em>. “What keeps me coming back is the Duaa, when you help the pilgrims, and they pray for you. It is such an amazing feeling.” Dr Mohammed Mattar Al Kaabi, Chairman of the General Authority of Islamic Affairs and Endowments and Head of the UAE Official Hajj Mission, thanked the Saudi government for welcoming the country's pilgrims and ensuring their safety. He said the Hajj set "a clear example of tolerance, peaceful coexistence, co-operation, mutual respect, compassion and fraternity regardless of cultural diversity and ethnicity".