As we are to understand from the verse, "The people who truly do believe in Our Signs are those who fall to the ground prostrating when they are reminded of them, and glorify their Lord with praise, and are not arrogant" (Surat as-Sajda: 15), one of the most important conditions of faith is modesty. Therefore, as this verse explains, believers are always modest, being aware that Allah does not love anyone who is vain or boastful (Surat an-Nisa' : 36):
And the servants of (Allah) Most Gracious are those who walk on the earth in humility, and when the ignorant address them, they say, "Peace!" (Surat al-Furqan: 63)
The morality of Islam entails submission to Allah, and submission entails acknowledgement of one' s weaknesses. Believers, who recognise that everything belongs to Allah, and that they themselves are weak and in need of Him, also act modestly towards Allah' s other faithful servants. Being arrogant is contrary to faith, and the Messenger of Allah (saas) tells the believers to be humble and to treat each other like brothers in a hadith:Do not envy one another; do not inflate prices one to another; do not hate one another; do not turn away from one another; and do not undercut one another, but be you. O servants of Allah, brothers. A Muslim is the brother of a Muslim: he neither oppresses him nor does he fail him, he neither lies to him nor does he hold him in contempt. Piety is right here -and the Prophet (saas) pointed to his breast three times. It is evil enough for a man to hold his brother Muslim in contempt. (Muslim)
Arrogance and modesty especially manifest themselves during human relations. The conduct of Iblis, as related in the Qur' an, best illustrates this point. Iblis refused to prostrate himself to the Prophet Adam. Being aware of Allah' s infinite might, it was illogical for him to openly claim superiority over Allah. But, it was his pride that was hurt. It was the Prophet Adam to whom he showed arrogance, and thereby exposed his rebellious intent towards Allah.
Consequently, arrogance, which is, in actuality, a sin against Allah, manifests itself during the relations of one person with another.
Surely, modesty also manifests itself under the same conditions. Believers show their submission to Allah by behaving modestly towards His believing servants. Aware of the fact that they are not responsible for the creation of their qualities, they are grateful to Allah, and never forget that Allah may reclaim any of these at any time. Fearing punishment from their Creator, Who is the Possessor of infinite power, they take refuge in no one but Him. This submissiveness of the believers, and their fear of Allah, is related in a verse as follows:
Say: "No one can protect me from Allah and I will never find any refuge apart from Him." (Surat al-Jinn: 22)