Commentary for Numbers 25:13

והיתה לו AND IT SHALL BE UNTO HIM — this covenant of Mine shall be unto him —

תחת אשר קנא לאלוקיו, seeing he had had the courage to fight My fight, I have ennobled him, granting him “peace” [a fitting reward for a noble fight. Ed.]

תחת אשר קנא לאלוקיו, because he displayed jealousy on behalf of His G'd. This verse provides the reason why G'd decided to give the priesthood to Pinchas as a gift rather than in his capacity of being the son of a priest. By pointing out that what Pinchas had done, he did on account of his G'd, G'd repaid him by elevating him to the priesthood as an act of honouring him personally. He did this by demonstrating that Pinchas did not have to rely on his ancestry, i.e his father and grandfather the High Priests in order to become a priest himself. ויכפר על בני ישראל, he atoned on behalf of the children of Israel. This means that he re-established peace between Israel and their Father in Heaven that G'd in turn called off the angel of death. Inasmuch as Pinchas had caused G'd to call off the angel of death from his people, his people made a pact of peace with him. Inasmuch as the benefits the Israelites derived from Pinchas' calling off the angel of death from them, in other words a benefit extending from generation to generation, Pinchas' elevation to the priesthood was also one that extended from generation to generation, i.e. כהונת עולם.