HOLY CITY OF MAKKAH, Saudi Arabia: Millions of Muslims making the annual pilgrimage to their holiest site, Makkah, flock to get a share of spring water that originates in heaven and is endowed with healing power.

The spring, named Zamzam, has run uninterrupted for some 4,000 years, from the time of Prophet Abraham and his son Prophet Ishmael.

The 31-metre (105-foot) deep source is located inside the Grand Mosque complex and its water is used to wash the holy Kaaba stone at the Grand Mosque ahead of the annual pilgrimage or hajj, which this year formally began on Monday.

Worshippers in the Grand Mosque are able to drink Zamzam from hundreds of scattered taps.

Because of belief in its healing power, there is a rush during every hajj -- when some two million Muslims converge on Makkah -- to collect some of the precious water for family members and friends who could not make the journey to Makkah.

Zamzam came into being to provide Hagar, Abraham's wife, and her baby Ishmael with water in the hot dry valley of Makkah where God ordered Abraham to leave them.

In her desperate search for water for the baby, Hagar ran seven times between the hillocks of Safa and Marwa until she saw water running between the legs of her baby.

Part of the hajj is called "Saiy", a run between Safa and Marwa in commemoration of Hagar's run in search of water.