Mishkat al-Masabih
Mishkat al-Masabih 433, 434
وَعَنْ أُمِّ سَلَمَةَ قَالَتْ قَالَتْ أُمُّ سُلَيْمٍ: يَا رَسُولَ اللَّهِ إِنَّ اللَّهَ لَا يَسْتَحْيِي مِنَ الْحَقِّ فَهَلْ عَلَى الْمَرْأَةِ من غسل إِذا احْتَلَمت قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ «إِذَا رَأَتِ الْمَاءَ» فَغَطَّتْ أُمُّ سَلَمَةَ وَجْهَهَا وَقَالَتْ يَا رَسُولَ اللَّهِ أَوَتَحْتَلِمُ الْمَرْأَةُ قَالَ: «نعم تربت يَمِينك فَبِمَ يشبهها وَلَدهَا؟» وَزَادَ مُسْلِمٌ بِرِوَايَةِ أُمِّ سُلَيْمٍ: «أَنَّ مَاءَ الرَّجُلِ غَلِيظٌ أَبْيَضُ وَمَاءَ الْمَرْأَةِ رَقِيقٌ أَصْفَرُ فَم أَيِّهِمَا عَلَا أَوْ سَبَقَ يَكُونُ مِنْهُ الشَّبَهُ»
Umm Salama reported that Umm Sulaym asked: ‘Messenger of Allah, Allah is not shy of the truth. Must a woman perform ritual bathing if she has a wet dream?’ The Prophet replied: ‘Yes, if she sees the fluid.’ Umm Salama covered her face and asked: ‘Messenger of Allah, can a woman have a wet dream?’ He replied: ‘Yes. How else would her child resemble her?’
Muslim added, in the version narrated by Umm Sulaym: ‘A man’s fluid is thick and white, and a woman’s fluid is thin and yellow. Whichever of the two prevails or comes first determines the resemblance.’