Appropriate modesty is a morality encouraged by religion.
The Holy Prophet Mohammad (pbuh&hh) said: “May Allah bestow His mercy on him who is modest to the Lord as he must be, who keeps both his mind and stomach safe from sin, who remembers his being worn out in his grave, and who reminds himself of his being raised in the hereafter.”
He (pbuh&hh) also said: “Modesty is of two kinds: The modesty of wisdom which brings knowledge and the modesty of foolishness which brings ignorance.”
Imam Ali (a.s.) the Commander of the Faithful said: “Impudence is the head of all evils.”
Imam Ali Zayn al-Abidin (a.s.) said: “A believer does not do any good thing to be seen, nor does he give it up for modesty.”
Imam Mohammad al-Baqir (a.s.) said: “Modesty and faith are tied up together; they are always to be found together.”
Imam Ja’far al-Sadiq (a.s.) said: “Modesty is a sign of faith; and faith takes you to paradise.”
He (a.s.) also said: “There is no faith for him who has no modesty.”
He (a.s.) also said: “The head of morality is modesty.”
He (a.s.) also said: “Do not abstain from learning because of modesty.”
Imam Musa al-Kazim (a.s.) said: “Surely Allah has forbidden paradise to him who is impudent and abusive, who has no modesty, who cares neither about what he says nor about what is said on him.”
source:english.almaaref