Majma al-Zawaid — Hadith 3379

Sayyiduna Mahmud bin Labid (may Allah be pleased with him), who belonged to Banu Abd al-Ashhal, said: The Prophet (peace and blessings be upon him) came to us in our mosque and led us in the Maghrib prayer. When he had said the salam at the end of the prayer, he said: "Pray these two rak'ahs in your homes." The Prophet (peace and blessings be upon him) said this about the voluntary prayer (that is, the sunnah) after Maghrib.
Ahmad recorded it, and its narrators are thiqat (trustworthy). Abdullah said: I said to my father (Imam Ahmad bin Hanbal): "A man has said: Whoever prays two rak'ahs in the mosque after Maghrib, his prayer is not valid; he must pray them in his home, because the Prophet (peace and blessings be upon him) said: 'This is one of the prayers of the home.'" Imam Ahmad asked: "Who said this?" I replied: "Muhammad bin Abd al-Rahman." He said: "How well he has spoken!" (the narrator is in doubt; perhaps the words are:) "How good is what he has transmitted, and how good is the ruling he has derived!"