Musar for Shabbat 127:9

In sight: Our sages, of blessed memory, said: "'from hand to hand he shall not escape from evil' (Mishlei 11:21), [this teaches] whoever counts out money from his hand to the hand of a woman in order to gaze at her, [even if he possesses Torah and good deeds like Moses our teacher,] shall not escape the punishment of Gehinom" (Berachot 61a). And: "why did the Jews of that generation require atonement? Because they fed their eyes with lewdness (Erva)" (Shab. 64b) and "Rabbi Sheshes said: 'Why does scripture enumerate the outward ornaments with the inner ones? To teach you: Whoever looks upon a woman's little finger is as though he gazed upon her private parts" (ibid).