For length of days, and long life,.... Or, "years of life", or "lives" ; a long life of usefulness and comfort here, and eternal life hereafter: the law of Moses promised a long life to the observers of it; but the Gospel of Christ brings an immortal life to light and promises to all believers in him that they shall not perish, but shall have everlasting life.
"Length of days for ever and ever" was asked by Christ of his Father, Ps 21:4, and given him, and is in his right hand, Pr 3:16; it is in his power to give, and he does give it to all his children, people, and followers, Ps 21:4;and peace shall they add to thee; the Gospel is the Gospel of peace, which not only proclaims peace by the blood of Christ; but the doctrines of it, such as justification by the righteousness of Christ, pardon by his blood, and atonement by his sacrifice, are the means of giving and increasing spiritual peace in the hearts of believers; and so are the ordinances of Christ, which in Pr 3:17; are called, for that reason, "paths of peace"; see Ro 5:1.