What did Malki-Tzedek and Avrohom learn from each other?
(14,18) “And Malki-Tzedek the king of Shalem brought out bread and wine, and he was a priest to G-d the Most High.”
I found the following explanation of this posuk in the sefer Imrei Kadosh in the name of R. Meir MiPremishlan:
We know from the Midrash and the gemora in Nedarim 32b that Malki-Tzedek was Shem the son of Noach, and the posuk tells us that he was the king of Yerushalayim and a priest to G-d the Most High. But why did the posuk interrupt these two descriptions of Malki-Tzedek in the middle with the words “brought out bread and wine”, and because of this it needed to add the phrase “and he” in order to continue with his description? The posuk should have first finished describing him, and then mention what he did!
But we can explain that the meaning of the posuk is that when two Tzaddikim meet, each one should endeavor to learn from the other the character trait which the other excels in more than him. And we know that Avrohom Avinu excelled in the trait of loving-kindness, taking in guests and giving them food and drink and whatever else they need. And Shem the son of Noach excelled in his service to Hashem, and for this reason he was called “priest of G-d the Most High”. So when these two Tzaddikim met up each one took from the other and tried very hard to acquire the superlative character trait that the other one had.
Therefore the posuk says that “Malki-Tzedek the king of Shalem brought out” from Avrohom the trait of “bread and wine” - the trait of looking after guests, “and he” - Avrohom - brought out (the phrase “brought out” refers to both parts of the sentence) from Shem the son of Noach the trait of being “priest to G-d the Most High” - the trait of serving Hashem.