The word of the Lord to the brother of Jared was an ultimatum, thou shalt not sin any more! With the brother of Jared, a prophet who had conversed with the Lord, this warning was particularly stern. However, this message is not just for a once negligent prophet, but to all repentant sinners. While we marvel at the wisdom of Jesus who dispelled the crowd ready to stone an adulterer, we sometimes forget that his last words to her were 'go, and sin no more' (Jn 8:11).
Spencer W. Kimball
"In all our expressions of wonder and gratitude at our Father's loving and forgiving attitude we must not be misled into supposing either that forgiveness may be considered lightly or that sin may be repeated with impunity after protestations of repentance. The Lord will indeed forgive, but he will not tolerate repetitions of the sin:
'And the Lord said unto him: I will forgive thee and thy brethren of their sins; but thou shalt not sin any more, for ye shall remember that my Spirit will not always strive with man; wherefore, if ye will sin until ye are fully ripe ye shall be cut off from the presence of the Lord.' (Eth. 2:15.)"
(The Miracle of Forgiveness, p. 357)