The Prophet of Islam said, "He who has pride in his heart, even equal to an atom, will not enter Paradise." A man enquired: "What about a person who likes fine dress and fine shoes?" He said: "God is Graceful, and He loves Grace. Pride amounts to disclaiming truth out of self-esteem and despising people." (Sahih Muslim, Hadith no, 91)
Arrogance means denying the bounty of God, and modesty means acknowledgement of God’s contribution. According to the Quran, the arrogant should be punished for their ungratefulness and the modest should be blessed with greater bounty.
This, moreover, is directly related to personality development. Arrogance vitiates one’s personality with negativity, while modesty creates positive thinking. There is a great difference between the two: negative thinking is the source of all kinds of evils, while positive thinking is the source of all kinds of goodness. Wise men are always modest in their behaviour.
The greatest minus point in an individual is arrogance, while the greatest plus point is modesty.