From twenty years old and upward. — Rashi thinks that these words were employed to show that the Levites who were numbered from a month old and upwards were not included in the general sentence of destruction, and hence that it is no just cause of astonishment that some of them, as, e.g., Eleazar, should have entered the land of Canaan.
Related Commentaries of Numbers 14:29
Numbers 14:29
29 Your carcases shall fall in this wilderness; and all that were numbered of you, according to your whole number, from twenty years old and upward, which have murmured against me,