Musnad Ahmad 86
Shu'bah said:
I heard 'Asim bin 'Amr al-Bajali narrate from one of those who asked ‘Umar bin al-Khattab. We have come to you to ask you about three things: A man's nafl prayer in his house, Ghusl in the case of janabah, and what it is appropriate for a man to do with his wife when she is menstruating. He said: Are you magicians? You have asked me about something that no one has asked me about since I asked the Messenger of Allah (ﷺ) about it, and he said:  `A man's nafl prayer in his house is light, so whoever wishes, let him illuminate his house.` And he said with regard to ghusl in the case of janabah: `Let him wash his private parts, then do wudoo', then pour water over his head three times.` And he said concerning the menstruating woman: `The [Husband may enjoy] whatever is above the izar (waist wrapper).`
حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، قَالَ سَمِعْتُ عَاصِمَ بْنَ عَمْرٍو الْبَجَلِيَّ، يُحَدِّثُ عَنْ رَجُلٍ، مِنْ الْقَوْمِ الَّذِينَ سَأَلُوا عُمَرَ بْنَ الْخَطَّابِ فَقَالُوا لَهُ إِنَّمَا أَتَيْنَاكَ نَسْأَلُكَ عَنْ ثَلَاثٍ، عَنْ صَلَاةِ الرَّجُلِ، فِي بَيْتِهِ تَطَوُّعًا وَعَنْ الْغُسْلِ، مِنْ الْجَنَابَةِ وَعَنْ الرَّجُلِ، مَا يَصْلُحُ لَهُ مِنْ امْرَأَتِهِ إِذَا كَانَتْ حَائِضًا فَقَالَ أَسُحَّارٌ أَنْتُمْ لَقَدْ سَأَلْتُمُونِي عَنْ شَيْءٍ مَا سَأَلَنِي عَنْهُ أَحَدٌ مُنْذُ سَأَلْتُ عَنْهُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ صَلَاةُ الرَّجُلِ فِي بَيْتِهِ تَطَوُّعًا نُورٌ فَمَنْ شَاءَ نَوَّرَ بَيْتَهُ وَقَالَ فِي الْغُسْلِ مِنْ الْجَنَابَةِ يَغْسِلُ فَرْجَهُ ثُمَّ يَتَوَضَّأُ ثُمَّ يُفِيضُ عَلَى رَأْسِهِ ثَلَاثًا وَقَالَ فِي الْحَائِضِ لَهُ مَا فَوْقَ الْإِزَارِ‏.‏