Musar zu Dewarim 6:12

Pride is the coin which the Great King, Blessed be He, voided, and about which He warned us in His Torah, as it is said: "Take care lest you forget the Lord your God and fail to keep His commandments" (Deut. 8:11). For the arrogant person forgets his Maker, as it is written, "… and (when) your herds and flocks have multiplied, and your silver and gold have increased, and everything you own has prospered, beware lest your heart grow haughty and you forget the Lord your God … and you say to yourselves, 'My own power and the might of my own hand have won this wealth for me'" (Ibid. 8:13-18). And in the case of a king it is said: "Thus he will not act haughtily towards his fellows or deviate from the Instruction to the right or to the left…" (Ibid. 17:20). If the Torah warned against pride even in the case of a king, so much more does it warn ordinary men that they should not attempt to lord over one another.