Sforno on Deuteronomy 6:25/ספורנו על דברים ו׳:כ״ה

1This 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.

2We will enjoy the transient life on this earth as a result of having first assured ourselves through observance of the commandments of our share in the world to come, i.e. eternal life.