And thine ears shall hear a word behind thee, saying, This is the way, walk ye in it, when ye turn to the right hand, and when ye turn to the left.- Isaiah 30:21
The word behind us which is spoken of in the text is mentioned as one among other covenant blessings. No “if” or “but” is joined to it. It is one of those gracious, unconditional promises upon which the salvation of the guilty depends. There are many comforts of the new life which depend upon our own action and behaviour, and these come to us with “ifs”; but those which are vital and essential are secured to the chosen of God without “but” or “peradventure.” It shall be so: God declares it shall, and He has power to carry out every jot and tittle of every promise that He makes to His people. I shall ask you at this good hour mainly to admire the free and sovereign grace of God in making such a promise as this to anybody, and especially in making it to a people whom He speaks of as “a rebellious people, lying children, children that will not hear the law of the Lord.” He severely upbraids them, and then in great patience He says to them, even to them, “Your ears shall hear a word behind you.” God’s grace is marvellous in itself, but its most marvellous point is the singular channel in which it chooses to flow: it runs down into the Dead Sea of sin and makes the waters pure.
God calls to the rebellious, and by his gentle word they are brought to his feet with repentance, turned from their evil wandering, and led in the way of obedience. ~ C.H. Spurgeon