The Greek verb eklanthanomai is an intensive compound of ek (completely) and lanthanomai (to forget), meaning to completely forget or be utterly oblivious. It appears only once in the NT (Hebrews 12:5), where the author quotes Proverbs 3:11 exhorting believers not to completely forget the Lord's exhortation when disciplined.
Hebrews 12 is one of the NT's most sustained passages on divine discipline (paideia). The author quotes Proverbs 3:11-12 and warns against two opposite errors: (1) despising discipline (treating it lightly), and (2) eklanthanomai — forgetting the exhortation entirely when fainting under hardship. Both extremes miss the point of suffering. God's discipline is proof of sonship (Hebrews 12:7-8). Pain in the life of a believer is not evidence of divine abandonment but of divine parenting. To completely forget this truth is to lose the interpretive key for understanding suffering and to miss the formation God is working through it.