Albert Barnes Commentary Galatians 3:9

"So then they that are of faith are blessed with the faithful Abraham." — Galatians 3:9 (ASV)

So then they which be of faith. They are those whose leading characteristic is that they believe. This was the leading trait in Abraham's character; and this is the primary thing required of those who embrace the gospel, and in the character of a true Christian.

Are blessed with faithful Abraham. In the same manner, they have a share in the promises made to him, and they will be treated as he was. They are justified in the same manner, and admitted to the same privileges on earth and in heaven.