Around two million Muslims gathered on Mount Arafat in Saudi Arabiainfo-icon on Thursday for the highlight of their Haj pilgrimage.

With temperatures pushing 40 degrees Celsius under the desert sun, the faithful climbed the hill east of Makkah on the second day of the pilgrimage, which is dedicated to prayer and reflection.

About 179,000 Pakistanis were among those who performed what is called the rukn-i-azam of Haj and listened to the sermon delivered from Masjid-i-Nimra by Imam Dr Shaykh Saa'd bin Nasir al-Shithri.

This year's Haj has seen the return of pilgrims from Iraninfo-icon following a diplomatic row between Tehraninfo-icon and Riyadh and a deadly stampede in 2015.

But thousands who would normally make the journey from neighbouring Qatarinfo-icon are absent apart from a few dozen because of the diplomatic crisis shaking the Gulf.

Iranian authorities say more than 86,000 Iranian pilgrims are taking part in the pilgrimage, each equipped with an identity bracelet in case of an accident.

Saudi Arabia says it has deployed more than 100,000 security personnel to keep pilgrims safe.

Helicopters flew around the area as the pilgrims converged from dawn on the Mount Arafat's plain and the hill known as Jabal al-Rahma.

Forming a sea of white, the pilgrims ascended the hill and took up positions to pray on rocks already heated by the morning sun.

Tunisian mother-of-three Fatima Arfawi said she was moved beyond words. "This is the first time I see anything like this, ever," she said. "This day is dedicated to prayer for my three children and my family."

In a hospital opposite the mountain, an area was set aside for people suffering dehydration or heat exhaustion.

Saudi Arabia's Red Crescent said it had deployed 326 ambulances along the pilgrimage route to handle healthinfo-icon emergencies.

Forge unity to tackle Ummah's challenges, Sheikh Saad

Sheikh Saad Bin Nasser al Shithri has urged Musliminfo-icon Ummah to forge unity in their ranks for addressing common challenges.

Dr Saad, who is member of the Council of Senior Scholars and adviser at the Royal Courtinfo-icon, delivered Hajjinfo-icon sermon at Masjid-e-Nimra in Arafat's on Thursday.

He asked Muslims to play their role to establish peace in the worldinfo-icon and not to commit excesses against each other and against non-Muslims.

 "Muslims should contribute to establish a society based on equality and free from ignorance and heresy," Sheikh Saad said, adding, "A Muslim society is based on discipline, which is the only way for progress and prosperity."

The Imam called on Muslims to act upon Sharia and follow the teachings of Holy Prophet (PBUH) for their salvation.

He prayed for the return of Masjid-e-Aqsa to Muslims and freedom of Palestinian people.