Kabbalah zu Bereschit 23:12

REGARDING HUMILITY So great is humility that Avraham, peace be upon him, was praised for it. This is because the people in his generation were great, and they had him as a prince, like Efron the Hitite, and they called him "my lord" etc (Genesis 23:15) and he diminished himself through the characteristic of humility and modesty among them, and even in front of the smallest of them, as it says "and Avraham bowed in front of the [simple] folk of the land" (Genesis 23:12).