1 Samuel 3:1-10 (NKJV):
Now the boy Samuel ministered to the Lord before Eli. And the word of the Lordwas rare in those days; there was no widespread revelation. 2 And it came to pass at that time, while Eli was lying down in his place, and when his eyes had begun to grow so dim that he could not see, 3 and before the lamp of God went out in the tabernacle of the Lord where the ark of God was, and while Samuel was lying down, 4 that the Lord called Samuel. And he answered, “Here I am!” 5 So he ran to Eli and said, “Here I am, for you called me.”
And he said, “I did not call; lie down again.” And he went and lay down.
6 Then the Lord called yet again, “Samuel!”
So Samuel arose and went to Eli, and said, “Here I am, for you called me.” He answered, “I did not call, my son; lie down again.” 7 (Now Samuel did not yet know the Lord, nor was the word of the Lord yet revealed to him.)
8 And the Lord called Samuel again the third time. So he arose and went to Eli, and said, “Here I am, for you did call me.”
Then Eli perceived that the Lord had called the boy. 9 Therefore Eli said to Samuel, “Go, lie down; and it shall be, if He calls you, that you must say, ‘Speak, Lord, for Your servant hears.’” So Samuel went and lay down in his place.
10 Now the Lord came and stood and called as at other times, “Samuel! Samuel!”
And Samuel answered, “Speak, for Your servant hears.”