Deuteronomy 4:40 KJV
Thou shalt keep therefore his statutes, and his commandments, which I command thee this day, that it may go well with thee, and with thy children after thee, and that thou mayest prolong thy days upon the earth, which the LORD thy God giveth thee, for ever.
Deuteronomy 4:38–42 KJV Chapter Context
38
To drive out nations from before thee greater and mightier than thou art, to bring thee in, to give thee their land for an inheritance, as it is this day.
39
Know therefore this day, and consider it in thine heart, that the LORD he is God in heaven above, and upon the earth beneath: there is none else.
40
Thou shalt keep therefore his statutes, and his commandments, which I command thee this day, that it may go well with thee, and with thy children after thee, and that thou mayest prolong thy days upon the earth, which the LORD thy God giveth thee, for ever.
41
Then Moses severed three cities on this side Jordan toward the sunrising;
42
That the slayer might flee thither, which should kill his neighbour unawares, and hated him not in times past; and that fleeing unto one of these cities he might live: