Albert Barnes Commentary Deuteronomy 33:20

"And of Gad he said, Blessed be he that enlargeth Gad: He dwelleth as a lioness, And teareth the arm, yea, the crown of the head." — Deuteronomy 33:20 (ASV)

That is, Blessed be God who shall grant to Gad a spacious territory. Compare the blessing of Shem (Genesis 9:26).

With the crown - Rather, indeed, the crown. The warlike character of this tribe is shown by their leading the van in the long campaigns of Joshua (Joshua 22:1–4). Compare also 1 Chronicles 5:18–22; 1 Chronicles 12:8 and following, and the acts of Jehu, the Gadite, in 2 Kings 9:0; 2 Kings 10:0.