عَنْ سَالِمٍ عَنْ أَبِيهِ رَضِيَ اللَّهُ عَنْهُ أَنَّهُ سَمِعَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ رَجُلًا يَعِظُ أَخَاهُ فِي الْحَيَاءِ فَقَالَ ((الْحَيَاءُ مِنَ الْإِيمَانِ))
It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him and his family) heard a man advising his brother regarding modesty. So the Prophet (peace and blessings be upon him and his family) said: Modesty is part of faith.