'Loins' in the Bible

nevertheless thou shalt not build the house; but thy son that shall come forth out of thy loins, he shall build the house unto my name.

And the young men that had grown up with him spoke to him saying, Thus shalt thou say to the people who have spoken to thee saying, Thy father made our yoke heavy, and lighten thou it for us, thus shalt thou say to them: My little finger is thicker than my father's loins;