Sforno on Deuteronomy 33:7/ספורנו על דברים ל״ג:ז׳

1וזאת ליהודה, this is also what I request and pray for on behalf of the people residing in the tribal territory of Yehudah that includes the members of the tribe of Shimon who were an enclave within the tribal territory of Yehudah. Let them not die in the wars in which they will be involved. They all go out to war together.

2ויאמר שמע ה' קול יהודה, in addition to what Moses had said under the heading of וזאת ליהודה, that whenever this tribe would pray to G’d either during war or any other occasion

3ידיו רב לו ועזר מצריו תהיה, though his own hands strive for him (during battle), help him against his foes.” I pray that You, G’d, be his hands, although to all intents and purposes people watching him may credit his own prowess with his victory.” רב לו, an expression of avenging wrong done to him. עזר מצריו, when they are attacking him and he is on the defensive.