Deuteronomy 30:20

20 in loving Jehovah thy God, in hearkening to his voice, and in cleaving to him -- for this is thy life and the length of thy days -- that thou mayest dwell in the land which Jehovah swore unto thy fathers, to Abraham, to Isaac, and to Jacob, to give them.

Deuteronomy 30:20 In-Context

18 I denounce unto you this day that ye shall surely perish; ye shall not prolong your days upon the land whereunto thou passest over the Jordan to possess it.
19 I call heaven and earth to witness this day against you: life and death have I set before you, blessing and cursing: choose then life, that thou mayest live, thou and thy seed,
20 in loving Jehovah thy God, in hearkening to his voice, and in cleaving to him -- for this is thy life and the length of thy days -- that thou mayest dwell in the land which Jehovah swore unto thy fathers, to Abraham, to Isaac, and to Jacob, to give them.
The Darby Translation is in the public domain.