The Messenger of Allah ﷺ said, "Obscenity never appears in anything without disgracing it, and modesty never appears in anything without adorning it."
حدثنا عبد الرزاق قال أخبرنا معمر عن ثابت
قال رسول الله ﷺ ما كان الفحش في شيء قط إلا شانه ولا كان الحياء في شيء قط إلا زانه
Its chain of transmission is sahih. It is found in Tirmidhi 4/349 no. 1974, in the chapter on righteousness, on what has been said about obscenity, where he said, hasan gharib, and in Ibn Majah 2/1400 no. 4185, in the chapter on abstinence, on modesty. It is also found in Muslim, from the hadith of Ayesha, with similar wording, 4/2004 no. 2594, in the chapter on righteousness, on the merit of gentleness.