Charles Ellicott Commentary 2 Kings 18:6

"For he clave to Jehovah; he departed not from following him, but kept his commandments, which Jehovah commanded Moses." — 2 Kings 18:6 (ASV)

For he clave. — And he held fast. Hezekiah’s pious feeling.

But kept. — And he kept. Hezekiah’s practice. The context shows that the “commandments” especially in the writer’s mind were those against polytheism.