Job 41
American Standard Version
24His heart is as firm as a stone; Yea, firm as the nether millstone.
Reina-Valera 1909
24Su corazón es firme como una piedra, y fuerte como la muela de abajo.
King James Version
24His heart is as firm as a stone; yea, as hard as a piece of the nether millstone.
World English Bible
24His heart is as firm as a stone, yes, firm as the lower millstone.