Take the Levites instead of all the firstborn among the
children of Israel
The Lord had declared before that he had taken them, and now he bids Moses take them, who had numbered them, and give them to Aaron, instead of the firstborn, whose numbers were also taken for this purpose:
and the cattle of the Levites instead of their cattle;
but not to be given to Aaron and his sons, or to the priests for their use, but to remain with the Levites for their use, who were now separated from the other tribes, and taken into the service of God; and as they were dedicated to God, so their cattle likewise for their support as his ministers:
and the Levites shall be mine;
in a special manner his, being devoted to his service:
I [am] the Lord;
who had a right to do this, and expected to be obeyed in it.