What is the ruling on an unlawful gaze in this world and the Hereafter?

The blessing of sight is among the blessings that require gratitude to Allah. Unrestrained gazing at forbidden things has harms, including falling into sin, the departure of the pleasure of worship, and being deprived of beneficial knowledge. Let the beholder know that Allah is observing him and knows the treachery of the eyes and what the breasts conceal.