Avraham Avinu / Abraham Our Forefather defeated the 4 kings who defeated 5 kings in a war.
Malki Tzedek – who was Shem – the son of Noach – came to greet him from his battle return with bread & wine.
He said Blessed is Avraham and Blessed is Hash-m / G-d. (Genesis 14:19)
Since he acknowledged and gave thanks to Avraham before acknowledging Hash-m, the priesthood was removed from MalkiTzedek and given to Avraham.
Someone did good to you?
Say Thank G-d & Thank You