Musar על אבות 4:19

When G–d spoke of the Israelites being His witnesses in Isaiah 43,10, this was an allusion to the good G–d will perform for the Jewish people in the days of the Messiah when He will renew the covenant with us -one that will never be severed- and one which will symbolise that Israel has been totally refined, both the patriarchs and their descendants. At that time the השגחה will be based on the Israelites being צדיקים בני צדיקים, righteous people descended from righteous people. Our sages have stated in Avot 4,19: "Nothing is in our hands: we can neither explain the prosperity of the lawless nor the sufferings of the righteous."