Albert Barnes Commentary 1 Kings 8:38

"what prayer and supplication soever be made by any man, [or] by all thy people Israel, who shall know every man the plague of his own heart, and spread forth his hands toward this house:" — 1 Kings 8:38 (ASV)

Know every man the plague of his own heart - that is, to perceive one’s sinfulness, or to recognize one’s sufferings as divine chastisements and sin as their cause.