MOUNT ARAFAT, Saudi Arabia -- Wearing white robes to symbolize purity and equality under God, millions of Muslims began their annual hajj pilgrimage Saturday by climbing a rocky desert hill outside Mecca.

Vast crowds of pilgrims started at dawn to ascend the Mountain of Mercy at Arafat, 12 miles (19 kilometers) outside Mecca, where Islam's Prophet Muhammad is said to have delivered his farewell sermon.

The ascent of Arafat is the first event associated with the five-day hajj, a time to seek forgiveness for one's sins and for individual meditation on the faith. Saudi authorities say that an estimated 2.5 million pilgrims are expected to participate.

Many prayed for peace at home as the Middle East faces an unprecedented wave of anti-government protests that has toppled autocrats in Tunisia, Egypt and Libya and shaken regimes in Yemen, Bahrain and Syria.

"I wish for security to be maintained in my country. I pray to God that we in Syria be unified and stand shoulder to shoulder," said sheik Ahmed Garman, 37, who led a group of Syrian pilgrims from Aleppo.

Syria since mid-March has witnessed a bloody crackdown on protesters in which the U.N. estimates some 3,000 people have been killed.

Saudi Arabia's top cleric, Grand Mufti Sheik Abdul-Aziz Al Sheik, said in his sermon that Islam "is facing challenges and divisions" and urged Muslims to "solve the problems only through peaceful means away from bloodshed."

"To the people I say: solve your problems by dialogue not through blood," Al Sheik told worshippers, who created a sea of white robes covering the streets and the mountain. "And to the leaders I say: you must consider God's dictation when you deal with your people."

The deadliest uprising was in Libya which started in February and led to a civil war that ended last month with the capture and death of longtime dictator Muammar Qaddafi.

At the Libyan tent camp, three balloons decorated with the revolutionary red, green and black flag hovered overhead with colorful lights flashing on the camp fences and tents. A red carpet covered the ground instead the signature green one that used to be imposed every year by Qaddafi's regime.

"Our revolution was watered with blood so we are using this color," said Abdul-Hamid Kashlaf, a 45-year old engineer from Tripoli.

Kashlaf and his wife were among around 7,000 Libyan pilgrims who lost loved ones in the conflict and were granted a free hajj trip by the National Transitional Council, which led the revolution and is now ruling the country.

His son, Abdul-Bari, was killed in Tripoli in August by pro-Qaddafi forces.

"I pray to God to grant us security and to put our country in the hands of good people," he said.

Since late Friday, pilgrims assembled around the mountain have been praying and reading Islam's holy book, the Quran. While many slept in tent compounds, others set up their small tents on sidewalks and streets. Charities and vendors along the way handed out food and umbrellas to shield the climbers from the harsh sun.

They chanted: "Labyek Allahum Labyek" -- or "Here I'm at thy service, my God, at thy service."

After sunset, the pilgrims will leave Arafat and headed to nearby Muzdalifah, where they collect pebbles for the next phase of the pilgrimage -- the symbolic stoning of the devil represented by three pillars in Mina, just to the west.

The pilgrims then slaughter a camel, sheep or cow to celebrate the beginning of the Eid al-Adha, or the "Feast of the Sacrifice."

Muslims from around the world wait a lifetime for a chance to make the pious journey in the footsteps of the Prophet Mohammed and Abraham, whom Muslims view as a forefather of Islam.

"I'm very happy today. I can't express my feelings," said Badr Olgach, a 41-year old construction contractor from Turkey. "I wish and pray for the best, for all the Prophet Muhammad's followers in the world," said the father of two.