Majma al-Zawaid — Hadith 1467

One of the people who had questioned Sayyiduna Umar (may Allah be pleased with him) narrates: Those people said to Sayyiduna Umar (may Allah be pleased with him): "We have come to you to ask you about three things: a man's offering voluntary prayer in his house, the ritual bath for janabah, and how far a man may be intimate with his wife when she is menstruating." Sayyiduna Umar (may Allah be pleased with him) said: "Are you sorcerers? Since I asked the Prophet (peace and blessings be upon him) about these things, no one has ever asked me about them, and now you have asked me (about these matters)." Then he said: "A man's offering voluntary prayer in his house is light, so whoever wishes may illuminate his house." In this narration he said: "The method of the ritual bath for janabah is that a man washes his private parts, performs ablution, and pours water over his head three times." About the menstruating woman he said: "He may be intimate with her above the waist-wrap." (Allamah al-Haythami says:) I say: Ibn Majah narrated from it the incident of "praying in the house".
Ahmad recorded it in this way through a man, from Amr, and he did not name that man.