'Day and Night' in the Bible

Let thy ear now be attentive, and thy eyes open, that thou mayest hear the prayer of thy servant, which I pray before thee now, day and night, for the children of Israel thy servants, and confess the sins of the children of Israel, which we have sinned against thee: both I and my father's house have sinned.

Nevertheless we made our prayer to our God, and set a watch against them day and night, because of them.