Musnad Ahmad 25:14

Hashim narrated to us, 'Awf informed us, from Ziyad ibn Husayn, from Abu al-'Aliyah, from Ibn 'Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said to me on the morning of Jam' (Muzdalifah): "Come, pick up [stones] for me." So I picked up for him small pebbles, the size of pebbles for throwing (at the Jamarat). When he placed them in his hand, he said: "Yes, with the likes of these. And beware of extremism in religion, for those who were before you were only destroyed by extremism in religion."