John Wesley on Deuteronomy 33:1

Moses blessed Israel - He is said to bless them, by praying to God with faith for his blessing upon them; and by foretelling the blessings which God would confer upon them. And Moses calls himself here the man of God, that is, the servant or prophet of God, to acquaint them that the following prophecies were not his own inventions, but divine inspirations. The children of Israel - The several tribes: only Simeon is omitted, either in detestation of their parent Simeon's bloody carriage, for which Jacob gives that tribe a curse rather than a blessing, in Gen 49:5 - 7. Or, because that tribe had no distinct inheritance, but was to have its portion in the tribe of Judah, Jos 19:1.