Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) relates: The Messenger of Allah (peace and blessings be upon him) came to us, with Usamah bin Zayd (may Allah be pleased with him) riding behind him, and we gave him this drink to drink, meaning the drink of the Siqayah (the giving of water to the pilgrims), and he (peace and blessings be upon him) said: "You have done well; keep doing it like this."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12878