Matthew Henry on 1 Samuel 3:19-21

All increase in wisdom and grace, is owing to the presence of God with us. God will graciously repeat his visits to those who receive them aright. Early piety will be the greatest honour of young people. Those who honour God he will honour. Let young people consider the piety of Samuel, and from him they will learn to remember their Creator in the days of their youth. Young children are capable of religion. Samuel is a proof that their waiting upon the Lord will be pleasing to him. He is a pattern of all those amiable tempers, which are the brightest ornament of youth, and a sure source of happiness.