Sunan Ibn Majah, Chapter: The Chapters on Dry Ablution

that Umm Sulaim asked the Messenger of Allah (saw) about a woman who sees in her dream something like that which a man sees. The Messenger of Allah (saw) 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 a 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)." (Sahih)