Question: In Parshas Pinchas it states that Pinchas was the grandson of Aharon the Kohen. It further states that because of his courageous deeds espoused in the Parsha, he was to be rewarded with everlasting ‘hereditary priesthood’ to include his descendants. In view of the fact that he was already a descendant of Aharon, did Pinchas not already have the blessing of ‘hereditary priesthood? How could this be considered a reward?
Answer: Hi! Rashi here says from the Gemara that not all descendants of Aharon would have been priests, just the ones born after the bestowal of the blessing. Pinchas, having been born already, needed a special appointment.
Another answer is provided by a midrash on Tanach. It says that although the high priest could be any descendant of Aharon, from the time of Shlomo haMelech onward every kohein gadol would be descended only from Pinchas. This is called here “bris Shalom”, covenant of peace: a play on the name Shlomo.