Jamieson, Fausset and Brown on Deuteronomy 1:39

39. your children ... who in that day had no knowledge between good and evil--All ancient versions read "to-day" instead of "that day"; and the sense is--"your children who now know," or "who know not as yet good or evil." As the children had not been partakers of the sinful outbreak, they were spared to obtain the privilege which their unbelieving parents had forfeited. God's ways are not as man's ways [Is 55:8, 9].