Charles Ellicott Commentary 2 Chronicles 6:30

"then hear thou from heaven thy dwelling-place and forgive, and render unto every man according to all his ways, whose heart thou knowest; (for thou, even thou only, knowest the hearts of the children of men;)" — 2 Chronicles 6:30 (ASV)

Every man. — The man. Distributive use of the article.

Whose heart you know. — Because you know his heart. Likewise in the Syriac and Arabic versions. The Vulgate has, “which you know him to have in his heart” (as if eth meant with, here).

The children of men. — All has dropped out. Likewise in some manuscripts, the Syriac and Arabic versions, and Kings.