Musnad Ahmad 32:282

Yazid narrated to us, Sa'id informed us, and Ibn Ja'far said: Sa'id narrated to us—the meaning being the same—from Qatadah, from Anas ibn Malik, that Umm Sulaym asked the Prophet, peace and blessings of Allah be upon him, about a woman who sees in her sleep what a man sees. The Prophet, peace and blessings of Allah be upon him, said: "Whoever among you sees that and experiences a discharge, let her perform ghusl (ritual bath)." Umm Salamah said: "Does that happen, O Messenger of Allah?" He said: "Yes. The man’s fluid is thick and white, and the woman’s fluid is yellow and thin. Whichever of them precedes or prevails, the child will resemble that one."