Sayyiduna Qurrah bin Iyas (may Allah be pleased with him) said: We were with the Prophet (peace and blessings be upon him) when modesty (haya) was mentioned in his (peace and blessings be upon him) presence. The people said: O Messenger of Allah! Is modesty part of the religion? The Messenger of Allah (peace and blessings be upon him) said: "Rather, it is the whole of the religion."
Then the Messenger of Allah (peace and blessings be upon him) said: "Indeed, modesty, chastity, and reticence of speech, which is a shortcoming of the tongue, not a shortcoming of the heart, and (good) deeds are all part of faith. They increase (a person) in the Hereafter and decrease (him) in this world, and what they increase in the Hereafter is far greater than what they decrease in this world. And miserliness and foul speech are part of hypocrisy; they increase (a person) in this world and decrease (him) in the Hereafter, and what they decrease in the Hereafter is far greater than what they increase in this world."
Hadith Referenceالمعجم الكبير للطبراني / باب القاف / 16113