Rashi on Deuteronomy 29:10/רש"י על דברים כ״ט:י׳

1מחטב עציך FROM THE WOODCUTTER [UNTO THE DRAWER OF THE WATER] — This teaches that some of the Canaanites came in Moses' days to become proselytes just as the Gibeonites came in the days of Joshua, — and this is the meaning of what is stated of the Gibeonites, (Joshua 9:4) “And they also acted cunningly”; — and Moses made them woodcutters and drawers of water (cf. Midrash Tanchuma, Nitzavim 2).