The Messenger of Allah ﷺ as saying: He who has in his heart as much pride as much pride as grain of mustard-seed will not enter paradise. And he who has in his heart as much faith as grain of mustard-seed will not enter Hell. Abu Dawud said: Al-Qasmali has transmitted it from Al-A'mash in a similar way.
قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَدْخُلُ الْجَنَّةَ مَنْ كَانَ فِي قَلْبِهِ مِثْقَالُ حَبَّةٍ مِنْ خَرْدَلٍ مِنْ كِبْرٍ وَلاَ يَدْخُلُ النَّارَ مَنْ كَانَ فِي قَلْبِهِ مِثْقَالُ خَرْدَلَةٍ مِنْ إِيمَانٍ