1 Samuel 3:7-9 NIV

7 Now Samuel did not yet know1 the LORD: The word2 of the LORD had not yet been revealed3 to him.

References for 1 Samuel 3:7

8 The LORD called Samuel a third time, and Samuel got up and went to Eli and said, "Here I am; you called me." Then Eli realized that the LORD was calling the boy.
9 So Eli told Samuel, "Go and lie down, and if he calls you, say, 'Speak, LORD, for your servant is listening.' " So Samuel went and lay down in his place.