Sahih Muslim Book - 3, Hadith - 715

حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى الرَّازِيُّ وَسَهْلُ بْنُ عُثْمَانَ وَأَبُو كُرَيْبٍ وَاللَّفْظُ لِأَبِي كُرَيْبٍ قَالَ سَهْلٌ حَدَّثَنَا و قَالَ الْآخَرَانِ أَخْبَرَنَا ابْنُ أَبِي زَائِدَةَ عَنْ أَبِيهِ عَنْ مُصْعَبِ بْنِ شَيْبَةَ عَنْ مُسَافِعِ بْنِ عَبْدِ اللَّهِ عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ عَنْ عَائِشَةَ أَنَّ امْرَأَةً قَالَتْ لِرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ هَلْ تَغْتَسِلُ الْمَرْأَةُ إِذَا احْتَلَمَتْ وَأَبْصَرَتْ الْمَاءَ؟ فَقَالَ نَعَمْ فَقَالَتْ لَهَا عَائِشَةُ تَرِبَتْ يَدَاكِ وَأُلَّتْ قَالَتْ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ دَعِيهَا وَهَلْ يَكُونُ الشَّبَهُ إِلَّا مِنْ قِبَلِ ذَلِكِ إِذَا عَلَا مَاؤُهَا مَاءَ الرَّجُلِ أَشْبَهَ الْوَلَدُ أَخْوَالَهُ وَإِذَا عَلَا مَاءُ الرَّجُلِ مَاءَهَا أَشْبَهَ أَعْمَامَهُ.

It was narrated from 'Aishah that a woman said to the Messenger of Allah (s.a.w): "Should a woman perform Ghusl if she has a wet dream and sees water?" He said: "Yes." 'Aishah said to her: "May your hands be rubbed with dust." The Messenger of Allah (s.a.w) said: "Let her be. Can the resemblance (of the child to either parent) come except through that? If her water prevails over that of the man, then the child will resemble his maternal uncles, and if the man's water prevails over hers, then he will resemble his paternal uncles."