Hebrews 4:11-12

Let us labour therefore to enter into that rest, lest any man fall after the same example of unbelief. {unbelief: or, disobedience} For the word of God {is} quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and {is} a discerner of the thoughts and intents of the heart.