Musnad Ahmad 32:1027

Isma'il narrated to us, Humayd narrated to us, from Anas, that it reached Abdullah ibn Salam that the Prophet, peace and blessings of Allah be upon him, had arrived in Medina. So he came to him and asked him about things. He said: "I am going to ask you about things that no one knows except a prophet." He said: "What is the first of the signs of the Hour? What is the first food that the people of Paradise will eat? And why does a child resemble his father, and why does a child resemble his mother?" He said: "Gabriel informed me of them just now." Ibn Salam said: "That is the enemy of the Jews among the angels." He said: "As for the first of the signs of the Hour, it is a fire that will gather them from the East to the West. As for the first food that the people of Paradise will eat, it is the caudate lobe of a whale's liver. And as for the child, if the man's fluid precedes the woman's fluid, the child resembles the father, and if the woman's fluid precedes the man's fluid, the child resembles the mother."