Musar do Liczb 32:6

ויתא ראשי עם צדקת ה' עשה ומשפטיו עם ישראל . I have heard a commentary according to which the tribe of Gad is praised for having conducted itself with more than the required amount of piety not only by marching with the other tribes in the war of conquest under the leadership of Joshua, but also by being in the vanguard. According to the agreement made with Moses In Numbers chapter 32 all that was required of this tribe was to put every able-bodied man under the joint command. This is why Moses says: ומשפטיו עם ישראל, "according to the law agreed with him he had to go with Israel." Gad, however, did more than was required, hence Moses mentions his צדקה, his righteousness.

The third element of repentance, that it be performed while a person is in his prime, when he is still subject to the temptation of the evil urge, is represented here by the tribe of Gad. The Mishnah in Avot 4,1, which describes a hero as a person who can conquer his passions, clearly shows that unless one has such passions, one does not qualify for the reward of having suppressed them. On Psalms 112,1, אשרי איש ירא את ה', "happy the man who fears the Lord," Rabbi Joshua ben Levi says that it refers to someone who does penitence while he is yet a man, in full possession of all his virility (Avodah Zarah 19a) [After all, why should a G–d-fearing woman not be described as happy? Ed.] The men of Gad were known as heroes. We know this from Genesis 49,19, when Jacob described him as turning the tables on any raiders. Compare Jerusalem Talmud Sotah 8,5. The heroism described there refers to his repentance, his sin having being due to his haste. Moses accused the members of that tribe by saying: "Shall your brothers go to war and you will sit it out here?" (Numbers 32,7) Note that although Gad was junior to Reuben, he was the first to make the request to stay in Trans-Jordan. Having been chastened by Moses, this tribe did more than it had been asked to do so as to compensate for its unbecoming conduct. This teaches that when repenting one should do so as wholeheartedly as the members of Gad and Reuven.