Book 24, Hadith 442

It was narrated that Ibn Abbas said:"On the morning of Al-Aqabah, while he was on his mount, the Messenger of Allh said: 'Pick up (some pebbles) for me.' So P picked up some pebbles for him that were the size of date stones of fingertips, and placed them in his hand. He started to do this with his hand." Yahya described him shaking them in his hand like this