ʿAbdullāh b. Mas’ūd – Allah be pleased with him – went to visit someone who was ill, and a group of people went with him. In the house (where they were visiting) was a woman. One of the visitors, a man, started to look at the woman. ʿAbdullāh [Ibn Mas’ūd] said to him, “If your eye had been gouged out (or popped out] it would have been better for you.”
Al-Bukhārī, Al-Adab Al-Mufrad. See Shaykh Al-Albānī’s Sahīh Al-Adab Al-Mufrad Vol.1 p212.