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
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.
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.