'Strength' in the Bible

But the first-born, son of the hated one, he doth acknowledge, to give to him a double portion of all that is found with him, for he is the beginning of his strength; to him is the right of the first-born.

Bless, O Jehovah, his strength, And the work of his hands Thou acceptest, Smite the loins of his withstanders, And of those hating him -- that they rise not!

Iron and brass are thy shoes, And as thy days -- thy strength.