Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.080B.

Upon completion of the seven rounds of the tawaf; and after offering the two rak’ahs by the Station of Ibrahim, it is encouraged to drink water from the well of Zamzam.

Both Bukhari and Muslim confirm that the Prophet (peace be upon him) drank of Zamzam water, and said, “It is blessed (water); it is food for the hungry, and a healing for the sick.’ It is reported that the angel Gabriel had washed the heart of the Prophet (peace be upon him) with its water on the Night Journey.

At-Tabarani in his Al-Kabir, and Ibn Hibban have reported from Ibn ‘Abbas that the Prophet (peace be upon him) said: ‘The best water on earth is the water of Zamzam. It is food for the hungry, and a healing for the sick.” (Al-Munzhri said that the chain of narrators of this hadith is sound)