A. Avraham’s main Avoda was to draw G-dliness into upper worlds:^[1]

Although our forefathers fulfilled the entire Torah even prior to it being given, nonetheless, their main divine service involved drawing G-dliness to the spiritual worlds above. Although of course they also drew down some of the infinite Divine light below into the physical world so there be a revelation of G-d in the world and in the hearts of man, who later became their followers, nonetheless, this does not compare to their main service of drawing Divine light to the upper worlds. This is the inner meaning behind the term used in Scripture regarding Avraham, “and he fulfilled my Mitzvah’s,” as Avraham fulfilled the Mitzvah’s on the level of G-d, in the world of Atzilus. This is the main novelty of the giving of the Torah to the Jewish people, to shift the focus from drawing G-dliness to the upper worlds to drawing G-dliness below to the physical world.

Avraham drew G-dliness into the upper worlds through kindness and humility: There were three actions performed by Avraham which caused the infinite light of G-d to be drawn into the upper worlds. The first is his love for G-d, the second is the kindness that he did with mankind in hosting guests, and the third is the humility that he had. These three actions which relate to kindness elicited G-dliness into the attribute of kindness that is found in the upper worlds.

[1] Torah Or p. 67b-