신명기 6:25 해설: Chizkuni, Ibn Ezra, Sforno & Or HaChaim

וצדקה תהיה לנו, “and it will be a righteousness for us, etc;” this verse has also not been spelled out completely; it should have read: 'וצדקה תהיה לנו לפני ה' אלוקינו כי נשמור וגו “and it will be a righteousness before the Lord our G-d, when we observe, etc.” in other words, Moses holds out the promises of a great reward for keeping the Torah. An alternate interpretation: this sentence is an appendage to the one that commenced with the question of the intelligent son in verse 20. Moses assures this son that there will be a great reward in store for him if he observes the various categories of commandments in the Torah about which he had enquired. This reward is the encouragement to diligently study and observe the Torah.

It will be our privilege Some say that this alludes to reward in the World to Come. Literally, though, it means that from the standpoint of strict justice, we are obliged to obey His will, because He is our Master. In my opinion the verse carries an additional meaning: All the nations will perceive that we are righteous, because we follow commandments and laws which are themselves righteous (for so it is written [4: 8]).

This is what I had in mind when I said to you וצדקה תהיה לו לטוב לנו כל הימים, it will be good for us not only in this life but will be a charitable act assuring us of life in the hereafter.