Musnad Abu Ya'la al-Mawsili 151:100

'Abd al-Wahid ibn Ghiyath narrated to us, 'Abd al-'Aziz ibn Muslim narrated to us, al-A'mash narrated to us, from Ibrahim, from 'Alqamah, from 'Abdullah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "He shall not enter Paradise who has in his heart the weight of a mustard seed of pride, and he shall not enter the Fire who has in his heart the weight of a mustard seed of faith."