'Day and Night' in the Bible

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

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