'Son's' in the Bible

Then Zipporah took a sharp stone, and cutting off the skin of her son's private parts, and touching his feet with it, she said, Truly you are a husband of blood to me.

And so that you may be able to give to your son and to your son's son the story of my wonders in Egypt, and the signs which I have done among them; so that you may see that I am the Lord.