Exodus 6:23 - Matthew Poole's English Annotations on the Holy Bible

Amminadab a prince of the tribe of Judah, Numbers 1:7 Numbers 2:3. Marriages were not yet confined to their own tribes; and when they were, the Levites seem to have had this privilege, that they might marry a daughter of any other tribe, because indeed the reason of that law did not concern them, there being no danger of confusion or loss of inheritance on their part. And especially there were many marriages made between the tribes of Judah and Levi, to signify that both were united in Christ, who was to be both king and priest. It is observable, that Moses is here silent in his own progeny, but gives a particular account of his brother s, not only from his great humility and modesty, which shines forth in many other passages, but because it was of more concernment; and the honour of priesthood given to Aaron was to be hereditary, and peculiar to his seed, and therefore it was necessary they should be exactly known; whereas Moses's honour and government was only personal, and did not pass to his children.