Humility leads one to kindness

The Rebbe Rashab writes:

Avrohom’s quality of bestowing kindness upon everyone stemmed from his total self-effacement. He regarded himself as having no importance, as it is written: “I am but dust and ashes” [Bereshis 18:27]. Since he considered every other person his better, he gave everything to others.

Sefer HaMa’amarim 5643, p. 9.

Kindness stems from a feeling of humility. The humble person feels undeserving of his prosperity. His humility also brings him to regard others favorably, and to assume that they are likely more worthy than he. Thus, he craves to share his wealth with others more worthy.

How can we explain this amazing statement, that Avrohom our forefather, the first Jew, genuinely considered all the degenerate pagans who would visit him, his betters?

Perhaps this can be explained based on the Rebbe’s explanation (Likkutei Sichos, Vol. 4, p. 1213) that one should also feel humble before a non-Jew, because he may have good qualities that one does not possess oneself, and in this regard the non-Jew is more worthy.