John Wesley on Isaiah 56:3

The stranger - The stranger, the Gentile, who by birth is a stranger to God, that hath turned from dumb idols to the living God. The eunuch - Who is here joined with the stranger, because he was forbidden to enter into the congregation of the Lord, Deut 23:1. Under these two instances he understands all those, who either by birth, or by any ceremonial pollution, were excluded from church privileges, and so he throws open the door to all true believers. A dry tree - A fruitless tree, accursed by God with the curse of barrenness.