1 Samuel 3:8
And the LORD called Samuel again the third time. And he arose and went to Eli, and said, Here am I; for thou didst call me. And Eli perceived that the LORD had called the child. And the LORD called Samuel again the third time. And he arose and went to Eli, and said, Here am I; for thou didst call me. And Eli perceived that the LORD had called the child.
On the third call Samuel arose and went to Eli saying Here am I, supposing Eli had called him and answering in the same way as before, and only after this third identical response did the aged Eli, who at first did not recognize the source, become convinced and perceive that the mysterious call was the voice of the Lord. The Lord had ceased to come to Eli and speak to Eli, passing by Eli, His chosen servant, an old man, to commune with a child. Eli was passed by because as parent and judge he neglected his duty, indulging his sons and failing to restrain their wrong habits and to separate them from holy office though they were unfitted for God's work, thereby dishonoring God, so that passing him by was itself a bitter yet deserved rebuke to Eli and his house.
Eli felt no envy or jealousy at being passed over for the child. To Samuel the Lord revealed what was to come upon Eli and his house, sending an angel to talk with him about the sins of Eli's sons corrupting Israel. Samuel was still a mere child educated for the Lord from a young age, surrounded by the most corrupting influences where Eli's sons ministered in holy office while controlled by Satan and polluted the whole atmosphere around them, with men and women daily fascinated by sin and wrong that filled all Israel with fearful reports, yet he walked untainted with spotless robes of character, having no fellowship with those sins and no delight in them, loving God and keeping his soul in close connection with Heaven, seeing not and hearing not evil.
Samuel's youth did not prevent God from addressing, instructing, revealing Himself to, preparing, and calling him, which proves God can communicate with and fit children who give themselves to Him to bear sacred truth and serve in sacred work as messengers, rather than speaking only to the elderly. The Lord claims young men as His helping hand, having called Samuel as a child to do a good and gracious work and to make known His message of truth, and his life is an example of what young people can do and what God expects from children and youth. The Lord likewise calls children and youth today to share that message and to rise up as an army of workers for Christ to do a work adults cannot do, because youth are more impressible so He can instruct them and mold their minds as He did Samuel's, while older persons sometimes become so set in their own course that, like Eli who received messages from God, they do not hear with a firm will to obey. This proves youth can hold principles so firm that Satan's most powerful temptations cannot draw them from allegiance, united to God and angels, not self-confident but knowing weakness and uniting ignorance to Christ's wisdom and weakness to His strength to fight the good fight of faith and lay hold on eternal life, a work no one can do for them.