1 Samuel 3:9

“Go and lie down,” he said to Samuel, “and if He calls you, say, ‘Speak, LORD, for Your servant is listening.’” So Samuel went and lay down in his place.

Therefore Eli said unto Samuel, Go, lie down: and it shall be, if he call thee, that thou shalt say, Speak, LORD; for thy servant heareth. So Samuel went and lay down in his place.