It is narrated from Umayr, the freed slave of Sayyiduna Umar (may Allah be pleased with him), that a group of the people of Iraq came to Sayyiduna Umar (may Allah be pleased with him). Umar (may Allah be pleased with him) said: Have you come with permission? They said: Yes. Umar (may Allah be pleased with him) said: What has brought you? They said: We have come to ask you three questions. He (may Allah be pleased with him) asked: What are they? They said: What is the ruling on a man offering voluntary prayer in his house? And what is permissible for him from his wife while she is menstruating? And they asked about the ritual bath (ghusl) for major ritual impurity (janabah). Sayyiduna Umar (may Allah be pleased with him) said: Are you sorcerers? They said: No, O Commander of the Believers, we are not sorcerers. He said: You have asked about three things about which no one has asked me since I asked the Messenger of Allah (peace and blessings be upon him) about them. "A man's prayer in his house is light, so light up your house as much as you are able; with a menstruating woman, (you may have) what is above the waist-wrap, and what is below it is not permissible for you; and as for the ritual bath for janabah: pour water with your right hand onto your left hand, then put your hand into the vessel, wash your private parts and whatever has stuck to them (remove it), then perform ablution like the ablution for prayer, then pour water over your head three times, rubbing your head each time, then wash the whole of your body."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1500