Muhammad bin Sirin (may Allah have mercy on him) said: Sayyiduna Uqbah bin Amir (may Allah be pleased with him) went to Maslamah bin Mukhallad, who was the governor of Egypt, and there was some (matter) between him and the (governor's) deputies. When he arrived, he went in to him, and he said: Welcome, my brother, you have come to visit me. He said: I have not come to visit you; rather, it is a hadith that I heard from the Messenger of Allah (peace and blessings be upon him), and you were with me that day. He (peace and blessings be upon him) said: "Whoever learns of a wrong done by his brother and conceals it for him, Allah Almighty will conceal (his faults) on the Day of Resurrection."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15033