Rashi on Genesis 14:18/רש"י על בראשית י״ד:י״ח

1ומלכי צדק AND MELCHIZEDEK — A Midrashic explanation is that he is identical with Shem, son of Noah (Nedarim 32b).

2לחם ויין BREAD AND WINE — Thus is done for those wearied through battle. He showed him (Abraham) that he bore him no malice for killing his descendants. The Midrashic explanation is that he (Melchizedek) thereby gave an intimation to him (Abraham) of the meal-offerings and libations which his descendants would offer there (in Salem which is Jeru-salem) (Genesis Rabbah 43:6).