Jamieson, Fausset and Brown on Genesis 5:24

24. And Enoch walked with God--a common phrase in Eastern countries denoting constant and familiar intercourse.

was not; for God took him--In He 11:5, we are informed that he was translated to heaven--a mighty miracle, designed to effect what ordinary means of instruction had failed to accomplish, gave a palpable proof to an age of almost universal unbelief that the doctrines which he had taught (Jude 14, 15) were true and that his devotedness to the cause of God and righteousness in the midst of opposition was highly pleasing to the mind of God.