The Posuk says “Do what is right and good in Hashem’s eyes, so that He will do good to you and you shall come and inherit the land”
Rashi states that the beginning of this posuk means that we should obligated to beyond the strict requirments of the Torah.
Our posuk then is bringing two different concepts together, to go beyond the letter of the law and to inherit the land. The question is why are these two concepts linked.
Rav Dovid Feinstein Shlita (the son of the Famous Rav Moshe Feinstien Ztl) says
that Chazal tell us the connection in the Gemora in Bava Metzia 30b where it says: “Jerusalem was destroyed because they did not judge there beyond the letter of the law”
The jews lost there land because they insisted on doing what was required… no more!