By praising God for enlarging Gad he supposeth the ground of these praises, that God would enlarge Gad, i.e. either.
1. Enlarge his territories; which seems needless, because they had a very large portion now when Moses uttered these words. Or,
2. Bring him out of his straits and troubles, which he was likely to be oft engaged in, because he was encompassed with potent enemies. And in this sense the phrase is used Psalms 4:1: compare Psalms 31:8, Psalms 118:5. One instance of the fulfilling hereof we have Jud 11. He dwelleth as a lion, i.e. safe and secure from his enemies, and terrible to them when they rouse and molest him. See 1 Chronicles 5:18, &c.; 1 Chronicles 12:8. Teareth the arm with the crown of the head, i.e. utterly destroys his enemies; both the head, the seat of the crown, their dignity and principality, and the arm, the subject of strength and instrument of action; both chief princes, and their instruments and subjects.