It was narrated from Salim that his father said:
"The Messenger of Allah ﷺ said heard a man urging his brother to be modest. He said: 'Indeed modesty is a branch of faith.'"

حَدَّثَنَا سَهْلُ بْنُ أَبِي سَهْلٍ، وَمُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ يَزِيدَ، قَالاَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، قَالَ سَمِعَ النَّبِيُّ ﷺ رَجُلاً يَعِظُ أَخَاهُ فِي الْحَيَاءِ فَقَالَ " إِنَّ الْحَيَاءَ شُعْبَةٌ مِنَ الإِيمَانِ " .