Deuteronomy 4:40 in the World English Bible
You shall keep his statutes and his commandments which I command you today, that it may go well with you and with your children after you, and that you may prolong your days in the land which the LORD your God gives you for all time.
Context
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;