It wasnarrated that Muhammad bin 'Abdur-Rahman bin Abu Bakr said:
"Iwas sitting with Ibn 'Abbas, and a man came to him and he said:'Wherehave you come from?' He said: 'From Zamzam.' He said:'Did you drinkfrom it as you should?' He said: 'How is that?'He said: 'When youdrink from it, turn to face the Qiblah andmention the name of Allah,drink three draughts and drink your fillof it. When you havefinished, then praise Allah.' The Messenger ofAllah (ﷺ) said: 'Thesign (that differentiates) between us andthe hypocrites is that theydo not drink their fill from Zamzam."
English reference: Vol. 4, Book 25, Hadith 3061
Arabic reference: Book 25, Hadith 3177