'Loins' in the Bible

Notwithstanding thou shalt not build the house; but thy son which shall come forth out of thy loins, he shall build the house for my name.

And the young men that were brought up with him spake unto him, saying, Thus shalt thou answer the people that spake unto thee, saying, Thy father made our yoke heavy, but make thou it somewhat lighter for us; thus shalt thou say unto them, My little finger shall be thicker than my father's loins.

Then Yahweh sent an angel, and he destroyed every mighty warrior of strength, commander, and officer in the camp of the king of Assyria. And he returned with shamed face to his land and went into the house of his god. And some of the offspring of his loins fell upon him there with the sword.