Now the boy Samuel was ministering to the LORD in the presence of Eli. And the word of the LORD was rare in those days; there was no frequent vision. — 1 Sa 3:1

Then the LORD said to Samuel, “Behold, I am about to do a thing in Israel at which the two ears of everyone who hears it will tingle. On that day I will fulfill against Eli all that I have spoken concerning his house, from beginning to end. And I declare to him that I am about to punish his house forever, for the iniquity that he knew, because his sons were blaspheming God, and he did not restrain them. Therefore I swear to the house of Eli that the iniquity of Eli’s house shall not be atoned for by sacrifice or offering forever.”
Samuel lay until morning; then he opened the doors of the house of the LORD. And Samuel was afraid to tell the vision to Eli. But Eli called Samuel and said, “Samuel, my son.” And he said, “Here I am.” And Eli said, “What was it that he told you? Do not hide it from me. May God do so to you and more also if you hide anything from me of all that he told you.” So Samuel told him everything and hid nothing from him. And he said, “It is the LORD. Let him do what seems good to him.”
And Samuel grew, and the LORD was with him and let none of his words fall to the ground. And all Israel from Dan to Beersheba knew that Samuel was established as a prophet of the LORD. — 1 Sa 3:11-20