אלשיך — ויצא מלך סדם לקראתו / ומלכי צדק מלך שלם

Q — Why does the Torah interrupt the flow between Melech Sdom going out to meet Avraham (v.17) and his actual conversation with him (v.21) by inserting Malki Tzedek's blessing in between?

A — The 'disorder' is deliberate. The Torah juxtaposes the two kings to expose the gap between them. The king of the city of 'רעים וחטאים' did not come out to greet Avraham when he set out to battle — only after the victory, and only after seeing the surrounding nations gathering at עמק שוה to crown Avraham; even then he came empty-handed, expecting to receive rather than to give. Malki Tzedek, by contrast — מלך שלם and כהן לאל עליון — brought לחם ויין to honor Avraham, though by his stature he should have been the one receiving honor. The Torah's editorial 'interruption' is the chiddush: side by side, the contrast preaches what kind of king Avraham's tradition will produce.