It is narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that he, Abu Dharr, Abu Sa'id al-Khudri and Muhammad bin Maslamah (may Allah be pleased with them) and one other man pledged allegiance to the Messenger of Allah (peace and blessings be upon him) that they would not care about the blame of any blamer in the matter of Allah.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5704