8Once again, for the third time, the LORD called to Samuel. He got up, went to Eli, and said, “Here I am, for you have called me.” Then Eli realized that it was the LORD who was calling the boy.
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.
10Then the LORD came and stood there, calling as before, “Samuel! Samuel!” And Samuel answered, “Speak, for Your servant is listening.”
— 1 Samuel 3:8-10