Another interpretation is that they will say, "The Redeemer of the Lord, who redeemed us." Or they will say, "The Redeemer of the Lord who will redeem them." Rabbi Yehuda, son of Rabbi Shalom, said, "How beautiful is the expression, for the statement of the Holy One, blessed be He, is fulfilled." Rabbi Huna said in the name of Rabbi Dostai, in the name of Rabbi Samuel bar Nachman and from another source, we learn that the statement of the Holy One, blessed be He, is a deed.
And from whom did we learn it? From Abraham. What is written? "On that day the Lord made a covenant with Abram, saying: 'To your descendants I have given this land'" (Genesis 15:18).
It only says "I have given," but did he already have children at that time? No, but the statement of the Holy One, blessed be He, is a deed. The Holy One, blessed be He, said, "I have said and I will do," and here too it says "The Redeemer of the Lord" because He has already redeemed them.