'Loins' in the Bible

“He loosens the bond of kingsAnd binds their loins with a girdle.

If his loins have not thanked me,And if he has not been warmed with the fleece of my sheep,

“Now gird up your loins like a man,And I will ask you, and you instruct Me!

“Now gird up your loins like a man;I will ask you, and you instruct Me.

“Behold now, his strength in his loinsAnd his power in the muscles of his belly.