Albert Barnes Commentary Deuteronomy 33:9

"Who said of his father, and of his mother, I have not seen him; Neither did he acknowledge his brethren, Nor knew he his own children: For they have observed thy word, And keep thy covenant." — Deuteronomy 33:9 (ASV)

Who said unto his father and to his mother - Compare (Matthew 10:37); (Luke 14:26).