Musnad Ahmad 26:363

'Affan narrated to us, 'Abd al-'Aziz ibn Muslim narrated to us, al-A'mash narrated to me, from Ibrahim, from 'Alqama, from 'Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "He will not enter Paradise who has in his heart the weight of a grain of pride, and he will not enter the Fire who has in his heart the weight of a grain of mustard seed of faith."