The first message that God gave to Samuel was a message of judgeement for the the house of Eli, Eli had not heeded the Lord's warning and so judgement was pronounced becasue Eli had not restrained his sons. Samuel of course was afraid to deliver this message to the spiritual leader of Israel, but Eli desired to hear what the Lord had to say to him. Therefore Samuel at Eli's request told him everything and when Eli heard the message he knew it was from the Lord and submitted to the word. From that time on Samuel's' fame began to spread as prophet and messenger of God and God revealed Himself to Samuel by His Word. But Samuel did not get proud or arrogant of the fact that God would use him but insteawd was humble before the Lord and thius the Lord could use him mightily.
