The phrase occurs only here in the New Testament. The works are those which Christ commands, which He does, and which are the fruits of His Spsrit. See on Joh 4:47.
Power (ἐξουσίαν)
See on Joh 1:12. Rev., better, authority.
Nations (ἐθνῶν)
See on Mat 25:32, and see on Gentiles, Luk 2:32. Properly, here, the Gentiles, as opposed to the true Israel of God.