Sunan Ibn Majah, Book 36, Hadith 82 (In-Book) ⓘ

It was narrated from Abu Sa’eed Al-Khudri that the Messenger of Allah stood up to deliver a sermon, and one of the things he said was: “Indeed, fear of people should not prevent a man from speaking the truth, if he knows it.” Then Abu Sa'eed wept and said: "By Allah, we have seen things that made us scared (and we did not speak up)."

حَدَّثَنَا عِمْرَانُ بْنُ مُوسَى، أَنْبَأَنَا حَمَّادُ بْنُ زَيْدٍ، حَدَّثَنَا عَلِيُّ بْنُ زَيْدِ بْنِ جُدْعَانَ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، أَنَّ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ قَامَ خَطِيبًا فَكَانَ فِيمَا قَالَ ‏ "‏ أَلاَ لاَ يَمْنَعَنَّ رَجُلاً هَيْبَةُ النَّاسِ أَنْ يَقُولَ بِحَقٍّ إِذَا عَلِمَهُ ‏" ‏ ‏.‏ قَالَ فَبَكَى أَبُو سَعِيدٍ وَقَالَ قَدْ وَاللَّهِ رَأَيْنَا أَشْيَاءَ فَهِبْنَا ‏.‏