Proverbs 20:20 New English Translation

²⁰The one who curses^[a] his father and his mother,
his lamp^[b] will be extinguished in the blackest^[c] darkness.

Proverbs 20:20 tn The form is the Piel participle of קָלַל (qalal), which means “to be light”; in the Piel stem it means “to take lightly; to treat as worthless; to treat contemptuously; to curse.” Under the Mosaic law such treatment of parents brought a death penalty (Exod 21:17; Lev 20:9; Deut 27:16).
Proverbs 20:20 tn “His lamp” is a figure known as hypocatastasis (an implied comparison) meaning “his life.” Cf. NLT “the lamp of your life”; TEV “your life will end like a lamp.”sn For the lamp to be extinguished would mean death (e.g., 13:9) and possibly also the removal of posterity (R. N. Whybray, Proverbs [CBC], 115).
Proverbs 20:20 tc The Kethib, followed by the LXX, Syriac, and Latin, has בְּאִישׁוֹן (b^eʾishon), “in the pupil of the eye darkness,” the dark spot of the eye. But the Qere has בֶּאֱשׁוּן (beʾeshun), probably to be rendered “pitch” or “blackest,” although the form occurs nowhere else. The meaning with either reading is approximately the same—deep darkness, which adds vividly to the figure of the lamp being snuffed out. This individual’s destruction will be total and final.

New English Translation (NET)