Musnad Ahmad 1065:10

Ibn Abi ‘Adi narrated to us, from Muhammad ibn Ishaq, [who said]: ‘Asim ibn ‘Umar ibn Qatadah narrated to me, from Mahmud ibn Labid, who said: The Messenger of Allah (peace and blessings of Allah be upon him) came to the Banu ‘Abd al-Ashhal and prayed Maghrib with them. When he had finished the prayer, he said: “Perform these two rak’ahs in your houses.” Abu ‘Abd al-Rahman [‘Abdullah ibn Ahmad] said: I said to my father [Imam Ahmad]: A man said: Whoever prays two rak’ahs after Maghrib in the mosque, it does not suffice him unless he prays them in his house, because the Prophet (peace and blessings of Allah be upon him) said: “These are among the prayers of the houses.” He [Imam Ahmad] said: Who said this? I said: Muhammad ibn ‘Abd al-Rahman. He said: How excellent is what he said, or how excellent is what he deduced.