Rava said, greater is that which is said regarding Moshe and Aharon, than that which is said regarding Avrohom. In Avrahom’s case it says, “I am mere dust and ashes,” while Moshe and Aharon said, “What are we?” (Chulin 89)
The Talmud refers to the level of humility reached by Moshe and Aharon as opposed to Avrohom. Avrohom felt that he had some value, that of dust and ashes, while Moshe and Aharon viewed themselves as having no worth at all. Rabbi Meir Shapiro Zt”‘l explains the differences between these great leaders in relation to whom they were speaking rather than to what they were comparing themselves. Avrohom was speaking to Hashem when he referred to himself as dust. Despite viewing himself as lowly and unpretentious, he nevertheless attached some significance to his being, even when compared to Hashem. Moshe and Aharon who said “what are we”, did not even value themselves as dirt when speaking to the complaining Jews. Even in comparison to these individuals they considered themselves worthless. Perhaps we can apply this explanation. Often a person will refuse to accept an offer to be honored by an organization. If the reason is his humility he is to be commended. However, often, he refuses these offers due to a lack of respect for those who are honoring him. He views these people with disdain as being below his dignity. Such an individual reflects an arrogance not befitting a Ben Torah.