Sahih al-Bukhari, Volume 8, Book 73, Hadith 139 (USC-MSA) ⓘ

Narrated `Abdullah bin `Umar: The Prophet passed by a man who was admonishing his brother regarding Haya' (pious shyness from committing religeous indiscretions) and was saying, "You are very shy, and I am afraid that might harm you." On that, Allah's Messenger said, "Leave him, for Haya' is (a part) of Faith."

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ أَبِي سَلَمَةَ، حَدَّثَنَا ابْنُ شِهَابٍ، عَنْ سَالِمٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما مَرَّ النَّبِيُّ صلى الله عليه وسلم عَلَى رَجُلٍ وَهْوَ يُعَاتَبُ فِي الْحَيَاءِ يَقُولُ إِنَّكَ لَتَسْتَحْيِي‏.‏ حَتَّى كَأَنَّهُ يَقُولُ قَدْ أَضَرَّ بِكَ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ دَعْهُ فَإِنَّ الْحَيَاءَ مِنَ الإِيمَانِ ‏" ‏‏.‏