“Incline your ear, and come unto me: hear, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David.”
King James Version (KJV)
55:3 An everlasting covenant - That everlasting covenant of grace and peace which I made with Abraham, and his seed. Of David - Even that covenant which was made first with Abraham, and then with David, concerning those glorious and sure blessings which God hath promised to his people, one and the chief of which was giving Christ to die for their sins. David here seems to be put for the son of David.