Is the Hadith: "Whoever fills his eyes with a woman unlawfully, Allah will fill them on the Day of Resurrection with fiery nails, and fill them with fire until He judges between people, then he will be ordered to the Fire" authentic? And what are the Hadith that mention the punishment for looking at people's 'awrat (private parts)?

The hadith, "Whoever fills his eyes with the unlawful, Allah will fill them with fire on the Day of Resurrection," is not found in the books of Sunnah. A weak hadith, which cannot be used as a proof, states: "And whoever casts an unlawful glance at a woman, Allah will fill his eyes with fire, then command him to the Fire." Other texts have warned against looking at 'awrat (private parts), among them: "Indeed, Allah has decreed for the son of Adam his share of zina (fornication/adultery), which he will inevitably attain; the zina of the eye is looking," and "No man should look at the 'awrah of another man, and no woman should look at the 'awrah of another woman," and "Do not follow one glance with another; for you is the first, but not the last."