Luke 23:42

said unto Jesus, &c.--Observe here (1) The "kingdom" referred to was one beyond the grave; for it is inconceivable that he should have expected Him to come down from the cross to erect any temporal kingdom. (2) This he calls Christ's own (Thy) kingdom. (3) As such, he sees in Christ the absolute right to dispose of that kingdom to whom He pleased. (4) He does not presume to ask a place in that kingdom, though that is what he means, but with a humility quite affecting, just says, "Lord, remember me when," &c. Yet was there mighty faith in that word. If Christ will but "think upon him" (Neh 5:19), at that august moment when He "cometh into His kingdom," it will do. "Only assure me that then Thou wilt not forget such a wretch as I, that once hung by Thy side, and I am content." Now contrast with this bright act of faith the darkness even of the apostles' minds, who could hardly be got to believe that their Master would die at all, who now were almost despairing of Him, and who when dead had almost buried their hopes in His grave. Consider, too, the man's previous disadvantages and bad life. And then mark how his faith comes out--not in protestations, "Lord, I cannot doubt, I am firmly persuaded that Thou art Lord of a kingdom, that death cannot disannul Thy title nor impede the assumption of it in due time," &c.

— Jamieson-Fausset-Brown Commentary (public domain)