1 Samuel 3: 1 - 10, 19 - 20
1 Now the boy Samuel was ministering to the LORD under Eli. And the word of the LORD was rare in those days; there was no frequent vision.
2 At that time Eli, whose eyesight had begun to grow dim, so that he could not see, was lying down in his own place;
3 the lamp of God had not yet gone out, and Samuel was lying down within the temple of the LORD, where the ark of God was.
4 Then the LORD called, "Samuel! Samuel!" and he said, "Here I am!"
5 and ran to Eli, and said, "Here I am, for you called me." But he said, "I did not call; lie down again." So he went and lay down.
6 And the LORD called again, "Samuel!" And Samuel arose and went to Eli, and said, "Here I am, for you called me." But he said, "I did not call, my son; lie down again."
7 Now Samuel did not yet know the LORD, and the word of the LORD had not yet been revealed to him.
8 And the LORD called Samuel again the third time. And he arose and went to Eli, and said, "Here I am, for you called me." Then Eli perceived that the LORD was calling the boy.
9 Therefore Eli said to Samuel, "Go, lie down; and if he calls you, you shall say, `Speak, LORD, for thy servant hears.'" So Samuel went and lay down in his place.
10 And the LORD came and stood forth, calling as at other times, "Samuel! Samuel!" And Samuel said, "Speak, for thy servant hears."
19 And Samuel grew, and the LORD was with him and let none of his words fall to the ground.
20 And all Israel from Dan to Beer-sheba knew that Samuel was established as a prophet of the LORD.

EWTN