Samuel grew - Increased to manhood.
The Lord was with him - Teaching him, and filling him with grace and holiness.
None of his words fall - Whatever prediction he uttered, God fulfilled it; and his counsels were received as coming from the Lord.

And Samuel grew, and the LORD was with him, and did let none of his words (l) fall to the ground.
(l) The Lord accomplished whatever he had said.

And Samuel grew,.... Not only in years and stature, but in grace and goodness, in wisdom, knowledge, and understanding, both with respect to things natural and spiritual, and in esteem, credit, and reputation among men:
and the Lord was with him; he was not only in favour with men, but with God; and had fresh and repeated tokens of the grace and good will of God towards him; he indulged him with his presence, and assisted him in his service, and prospered and succeeded him in all things in which he was engaged. The Targum is,"the Word of the Lord was his help;''the essential Word of God, the Messiah:
and did let none of his words fall to the ground (x); in allusion either to water that falls to the ground, and becomes useless, or to an arrow falling out of the bow, and to the ground, before it reaches the mark, and so unsuccessful (y); or to any weapon of war, sword or spear, falling out of the hand of the soldier, whereby he is disarmed and rendered unserviceable: and these words, according to Kimchi, and in which he is followed by Abarbinel, are to be understood, not only of the words which he spake by the Holy Ghost under a spirit of prophecy, and had their exact accomplishment; but his common words, which were spoken by weight and measure, as the last expresses it, and which were delivered out according to the rules of justice, probity, and truth; and so he failed not of performing that which he had said, or of doing what was right, whereby Israel knew he was fit, prepared, and designed to be a prophet of the Lord, as in the following verse; but it seems rather to have respect to the things predicted by him under a spirit of prophecy concerning Eli and his house, which soon began to be fulfilled.
(x) , Pindar. Pythia, Ode 6. (y) Vid. Homer. Iliad. 17. ver. 633.

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.

Thus Samuel grew, and Jehovah was with him, and let none of his words fall to the ground, i.e., left no word unfulfilled which He spoke through Samuel. (On הפּיל, see Joshua 21:45; Joshua 23:14; 1-Kings 8:56.) By this all Israel from Daniel to Beersheba (see at Judges 20:1) perceived that Samuel was found trustworthy, or approved (see Numbers 12:7) as a prophet of Jehovah. And the Lord continued to appear at Shiloh; for He revealed himself there to Samuel "in the word of Jehovah," i.e., through a prophetic announcement of His word. These three verses form the transition from the call of Samuel to the following account of his prophetic labours in Israel. At the close of 1-Samuel 3:21, the lxx have appended a general remark concerning Eli and his sons, which, regarded as a deduction from the context, answers no doubt to the paraphrastic treatment of our book in that version, but in a critical aspect is utterly worthless.

Fail, &c. - That is, want its effect: God made good all his predictions. A metaphor from precious liquors, which when they are spilt upon the ground, are altogether useless.