Musnad Ahmad 437:2

Abdullah ibn Ahmad said: I read this hadith to my father: Abbad ibn Abbad and Ibn Abi Adi narrated to us, from Ibn Awn, from Makhul, that Uqbah—Ibn Abi Adi said—came to Maslamah ibn Mukhallad in Egypt. There was something between him and the doorkeeper, and he heard his voice, so he gave him permission to enter. He said: "I did not come to you as a visitor, but I came to you for a need. Do you remember the day—Abbad said in his hadith—the Messenger of Allah (peace and blessings of Allah be upon him) said: 'Whoever knows of a bad deed from his brother and conceals it, Allah the Almighty will conceal him by it on the Day of Resurrection'?" He said: "Yes." He said: "That is why I came." Ibn Abi Adi said in his hadith: Uqbah ibn Amir rode to Maslamah ibn Mukhallad, and he was the governor of Egypt.