When two million Muslim pilgrims descend upon Mecca each year, Saudi Arabia finds its strict version of Islam put to the test.
The desert kingdom, where the religion of over one billion Muslims originated, applies a strict form of Sunni Islam which most believers consider overzealous and unusual.
The contrast between Islam's different traditions is stark during the haj, a once-in-a-lifetime duty for every able-bodied Muslim of every sect, during which Mecca is transformed into the focal point for Muslims from places as diverse as Indonesia, Burkina Faso and Russia.
Saudi Islam, often termed Wahhabism after its founding father Mohammed bin Abdel Wahhab, imposes strict gender segregation, forces shops to close during prayer times, forbids visiting graves, and shuns women driving or singing.
"There are general instructions not to interfere too much with pilgrims during the haj," said Saudi writer Mansour Nogaidan, a critic of Wahhabi Islam.
Religious authorities warn pilgrims in booklets and signs in different languages not to engage in acts which venerate individuals such as the Prophet Mohammed or pilgrimage sites -- considered one step away from the idolatry rejected by Islam.
But pilgrims performing tawaf, or circumambulation of the Kaaba in Mecca's Grand Mosque, make for the ancient structure, rubbing and kissing it in search of God's favor and in the hope that the Almighty will hear their prayers.
The sheer volume of the crowds forces Saudi Arabia's special morality police to take a back seat during rituals where men and women rub shoulders and pray together.
"Don't pray here, don't pray here!" one shouted at men and women who took to the ground in prayer next to the Kaaba as a crush of pilgrims walked around this week.
Pilgrims also ignore pleas not to emulate the Prophet by climbing up Mount Arafat to the exact site of his last sermon.
At stoning-of-the-devil rites which take place during the last three days of the haj, which ends on Saturday, many pilgrims put what Wahhabis view as too much passion into the ritual which is meant to symbolize the cleansing of sins.
"There are some who go too far and for whom throwing stones at these pillars is everything," said Saudi Khaled al-Najashi.
"But it is only an obligation that we must carry out, and you shouldn't be overzealous about it," he said, reflecting a puritanism which can appear colorless to many followers of other Islamic traditions.
"Their Islam is very dry, there's something missing. They have such a sense of orthodoxy and control," said a South African imam, citing the other, more relaxed Islamic schools.
Wahhabism stems from the most conservative of four schools of Sunni Islam. The other three branches are more tolerant of Shi'ite and mystical Sufi Islam, as well as other religions.
After 250 pilgrims were crushed to death at the stoning rite last year, the authorities encouraged pilgrims to perform the ritual at different times than those advocated by Saudi clerics.
"They went with the opinion of Egypt's al-Azhar, but there are still a lot of clerics here not happy about it," Nogaidan said, referring to Sunni Islam's highest seat of learning which is based in Cairo.
"Clerics here need to realize that Islam isn't one form and the world is more diverse than they want to accept. But they want to impose their idea of Utopia on us all."