Deuteronomy 11:8

Still Moses urges the same subject, as loth to conclude till he had gained his point. "If thou wilt enter into life, if thou wilt enter into Canaan, a type of that life, and find it a good land indeed to thee, keep the commandments: Keep all the commandments which I command you this day; love God, and serve him with all your heart." I. Because this was the way to get and keep possession of the promised land. 1. It was the way to get possession (Deu 11:8): That you may be strong for war, and so go in and possess it. So little did they know either of hardship or hazard in the wars of Canaan that he does not say they should go in and fight for it; no, they had nothing in effect to do but go in and possess it. He does not go about to teach them the art of war, how to draw the bow, and use the sword, and keep ranks, that they might be strong, and go in and possess the land; no, but let them keep God's commandments, and their religion, while they are true to it, will be their strength, and secure their success. (2.) It was the way to keep possession (Deu 11:9): That you may prolong your days in this land that your eye is upon.

— Matthew Henry's Concise Commentary (public domain)