Abu Hayyan narrates from his father that once Sayyiduna Ibn Amr (may Allah be pleased with him) and Sayyiduna Ibn Umar (may Allah be pleased with them both) met. After a short while, when Sayyiduna Ibn Umar (may Allah be pleased with them both) returned, he was crying. People asked him, "O Abu Abdur Rahman, why are you crying?" He replied: "Because of the hadith that he narrated to me, that I heard the Noble Prophet (peace and blessings be upon him) say: That person will not enter Paradise in whose heart there is even a mustard seed's weight of arrogance."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6526