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Millions of pilgrims in Saudi Arabia on Friday furiously cast pebbles in a symbolic stoning of the devil, carrying out a final rite of hajj, as Muslims around the world celebrated the start of Islam's biggest holiday, the Feast of Sacrifice.

After stoning three walls symbolizing Satan in a rejection of sin and temptation, male pilgrims changed out of the seamless terrycloth robes of pilgrimage and shaved their heads, as a sign of renewal. Women — and those men who prefer not to undergo a complete shave — had a lock of hair clipped.

Though pilgrims will repeat the stoning ritual for at least two more days, they could now call themselves "hajjis," referring to those who have done the pilgrimage.

Malik Evangelatos, from Ukiah, Calif., said the experience felt "wonderful, satisfying and humbling."

Evangelatos, who converted to Islam six years ago, said the simple pilgrim's garment that he had worn the past few days helped him "see the bigger picture in life and go back changed, happy and appreciative." For him, the hajj brought a chance to be truly equal regardless of ethnicity or race.

"It has probably been the highlight of my life outside of getting married and having a baby," he said. "You feel an emotional release. It is something that is not recreated anywhere else in the world."

For the stoning ritual, the 3.4 million pilgrims from around the world filed in crowds through a multi-level structure housing the walls symbolizing the devil in the desert valley of Mina, outside the holy city of Mecca.

The structure of ramps maintains traffic flow, moving pilgrims on four levels past the walls, as they throw seven pebbles at each. Some have criticized the nearly kilometer-long (0.6 mile) cement structure, which resembles a mega parking garage with escalators, saying it detracts from the simplicity and spiritual aspect of hajj.

But the facility protects lives, Hajj Ministry Director General Amin Fatani, told The Associated Press. The stoning ritual has been the scene of deadly crushes and stampedes killing hundreds — the most recent in 2006 — as pilgrims tried to squeeze past and throw their stones, especially since there used to be pillars instead of walls, meaning the massive throngs had to focus on a smaller point. Even with the walls, pilgrims on one side often get hit by pebbles thrown by people on the other side.

"The life of a hajji is precious to the government and their safety comes first," Fatani said. "If we leave hajj the way we had it been before, there will be a catastrophe from the first day."

On Friday, Muslims marked the holiday, known in Arabic as Eid al-Adha, commemorating what Muslims believe was Prophet Abraham's willingness to sacrifice his son Ismail — the Biblical Ishmael, though Christians and Jews believe his other son Isaac was the near-sacrifice — as a test of his faith from God.

Around the world, Muslims slaughtered lambs, sheep and other livestock in remembrance, giving the meat to the poor. At Mina, pilgrims purchased tokens to have a sheep slaughtered at nearby slaughterhouses.

The day of stoning marked an exhausting trek for pilgrims between the string of ritual sites strung across the desert outside Mecca. They spent the day Thursday at Mount Arafat in a day of contemplation and prayers to wipe away past sins. Then overnight, they went to the nearby plain of Muzdalifah to collect the pebbles they would use in the stoning ritual before heading to Mina by the morning.

Between the movements, many also went back into Mecca to again circumambulate the Kaaba, the cube-shaped structure toward which Muslims pray every day — Islam's holiest site.

Tunisian pharmacist Ahlam Zahar said she teared up seeing the sheer number of people praying in unison as she approached the Kaaba late Thursday before coming to Mina for the stoning on Friday.

"Hajj needs energy and concentration," she said. "It's really hard under the heat."

For most pilgrims coming from poorer Muslim nations, it is common to sleep in the streets and walk the trajectory among the sites, a distance of around 30 kilometers (19 miles). Many have children or elderly relatives with them.

"I envy them," Ahmed Fahmy said of those enduring the difficult trek. "These people are following the footsteps of the Prophet (Muhammad). They could manage to get rides, but they exhaust themselves for the bigger reward with Allah."

Fahmy, the general manager of the Cairo-based Islamic Huda TV, said this was his 11th Hajj to complete. Despite feeling tired afterward, the reward of the pilgrimage is in the hardship one faces, he said.

"You feel obedient to Allah," Fahmy said. "I feel like it's something that is entirely for the pleasure of Allah."