תהילים קיב:ד פירוש: רש״י

He shone a light in the darkness Heb. זרח [the “kal” conjugation], like הזריח, [the “hiph’il” or causative conjugation]. Its midrashic interpretation is that He Himself, so to speak, becomes a light for them, as (above 27:1): “The Lord is my light and my salvation.”