Deuteronomy 33:9

Who said unto his father and to his mother, I have not seen
him
Which some understand of the high priests who were of this tribe, and according to the law were not to defile themselves, or mourn for a father or mother, ( Leviticus 21:11 ) ; or rather, as others, of their having no respect to them in judgment, but determining all causes that came before them according to the law of God, and the rules of justice and equity, in the most impartial manner, without having any regard to the nearest relations to them: with this compare what Christ the antitype of Levi says, in ( Matthew 12:49 Matthew 12:50 ) ;

neither did he acknowledge his brethren, nor knew his own children;
had no respect to persons in judgment, though ever so nearly related: many restrain this to the affair of the golden calf, when the tribe of Levi gathered together, girded their swords on their thighs, and slew every man his brother, companion, and neighbour, guilty of that idolatry, ( Exodus 32:26 Exodus 32:27 ) ;

for they have observed thy word, and kept thy covenant;
the law of God, spoken by him, and had the nature of a covenant with the people of Israel: this the tribe of Levi observed, not only what respects the worship of God, and the contrary to it, idolatry, but all other moral and religious duties; Christ fulfilled the whole law, and did always and all things what pleased the Lord, ( John 8:29 ) .