Sunan Ibn Majah 58
سنن ابن ماجه#58Sahihحَدَّثَنَا سَهْلُ بْنُ أَبِي سَهْلٍ، وَمُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ يَزِيدَ، قَالاَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، قَالَ سَمِعَ النَّبِيُّ ـ صلى الله عليه وسلم ـ رَجُلاً يَعِظُ أَخَاهُ فِي الْحَيَاءِ فَقَالَ " إِنَّ الْحَيَاءَ شُعْبَةٌ مِنَ الإِيمَانِ " .
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
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim