9 For we do not by our deservings prevent the mercy of God; but, “The Lord has been mindful of us, and has blessed us. He has blessed the house of Israel, He has blessed the house of Aaron”. But in blessing both of these, “He has blessed all that fear the Lord”. Do you ask, who are meant by both of these? He answers, “both small and great.” That is, the house of Israel with the house of Aaron, those who among that nation believed in Jesus the Saviour....For in the character of those who out of that nation believed, it is said, “Except the Lord of Sabaoth had left us a seed, we had been as Sodoma, and been made like Gomorrha.” Seed, because when it has been scattered over the earth, it multiplied.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)