It is related about Sayyiduna Maslamah bin Mukhallad (may Allah be pleased with him) that Sayyiduna Uqbah bin Amir (may Allah be pleased with him) came to him, and there was some ill feeling between Uqbah and the gatekeeper. He heard the visitor's voice and gave him permission to enter. He said: "I have not come to you to visit; rather, I have come to you with a need. Do you remember the day the Messenger of Allah (peace and blessings be upon him) said: 'Whoever learns of a fault of his brother and then conceals it, Allah will conceal him on the Day of Resurrection'?" He said: "Yes." He said: "It is for this that I have come."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17116