Musnad Ahmad 28:537

Marwan ibn Shuja‘ Abu ‘Amr al-Jazari narrated to us, Ibrahim ibn Abi ‘Ablah al-‘Uqayli, from the people of Jerusalem, narrated to me, from Abu Salamah ibn ‘Abd al-Rahman ibn ‘Awf, who said: ‘Abdullah ibn ‘Umar and ‘Abdullah ibn ‘Amr ibn al-‘As met at al-Marwah and spoke together. Then ‘Abdullah ibn ‘Amr departed, and ‘Abdullah ibn ‘Umar remained weeping. A man said to him: "What makes you weep, O Abu ‘Abd al-Rahman?" He said: "This one"—meaning ‘Abdullah ibn ‘Amr—"claimed that he heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever has in his heart the weight of a mustard seed of pride, Allah will cast him upon his face into the Fire.'"