Abu Salam said: Abu Asmaa Al-Rahabi told us that Thawban, the freed slave of the Messenger of Allah (SAW), related to him saying: I was standing with the Messenger of Allah (SAW) and one of the Jewish leaders came ... He said: I have come to ask you about something which no one on Earth knows except a prophet or one or two others. He [Messenger of Allah] said: Will it benefit you if I tell you? He said: I lend my ears; and then said: I have come to ask you about children. He said: The man’s fluid is white and the woman’s fluid is yellow, and if they both come together and the man’s semen [maniy] prevails over the woman’s semen [maniy], they have made a male child by the permission of Allah; and if the woman’s semen prevails over the man’s semen, they have made a female by the permission of Allah. The Jew said: You have spoken rightly; indeed you are a prophet. Then he left and went away. And the Messenger of Allah (SAW) said: He asked me about what he asked me, of which I did not know anything until Allah brought it to me.