It was narrated from Anas that:
Umm Sulaim asked the Messenger of Allah about a woman who sees in her dream something like that which a man sees. The Messenger of Allah said: "If she sees that and has a discharge, then let her perform a bath." Umm Salamah said: "O Messenger of Allah, does that really happen?" He said: "Yes, the water of the man is thick and white and the water of a woman is thin and yellow. Whichever of them comes first or predominates, the child will resemble (that parent)."

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، وَعَبْدُ الأَعْلَى، عَنْ سَعِيدِ بْنِ أَبِي عَرُوبَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ أُمَّ سُلَيْمٍ، سَأَلَتْ رَسُولَ اللَّهِ ﷺ عَنِ الْمَرْأَةِ تَرَى فِي مَنَامِهَا مَا يَرَى الرَّجُلُ فَقَالَ رَسُولُ اللَّهِ ﷺ " إِذَا رَأَتْ ذَلِكَ فَأَنْزَلَتْ فَعَلَيْهَا الْغُسْلُ " . فَقَالَتْ أُمُّ سَلَمَةَ يَا رَسُولَ اللَّهِ أَيَكُونُ هَذَا قَالَ " نَعَمْ مَاءُ الرَّجُلِ غَلِيظٌ أَبْيَضُ وَمَاءُ الْمَرْأَةِ رَقِيقٌ أَصْفَرُ فَأَيُّهُمَا سَبَقَ أَوْ عَلاَ أَشْبَهَهُ الْوَلَدُ " .