Verses 32, 33. - On being brought before the king, David says, Let no man's heart fail because of him, i.e. "on account of this Philistine." Literally it is "upon him," and some therefore translate "within him." The Septuagint forman reads "my lord" - "Let not my lord's heart fail within him." Probably "within him" is the best rendering of the phrase. Thou art but a youth. I.e. "a lad" (see on 1 Samuel 1:24; 2:18). It is the word applied to David's brethren in 1 Samuel 16:11, and his friend must have been very enthusiastic when, in 1 Samuel 16:18, he described him as a "hero of valour and a man of war."

17:31-39 A shepherd lad, come the same morning from keeping sheep, had more courage than all the mighty men of Israel. Thus God often sends good words to his Israel, and does great things for them, by the weak and foolish things of the world. As he had answered his brother's passion with meekness, so David answered Saul's fear with faith. When David kept sheep, he proved himself very careful and tender of his flock. This reminds us of Christ, the good Shepherd, who not only ventured, but laid down his life for the sheep. Our experience ought to encourage us to trust in God, and be bold in the way of duty. He that has delivered, does and will continue to do so. David gained leave to fight the Philistine. Not being used to such armour as Saul put upon him, he was not satisfied to go in that manner; this was from the Lord, that it might more plainly appear he fought and conquered in faith, and that the victory was from Him who works by the feeblest and most despised means and instruments. It is not to be inquired how excellent any thing is, but how proper. Let Saul's coat be ever so rich, and his armour ever so strong, what is David the better if they fit him not? But faith, prayer, truth, and righteousness; the whole armour of God, and the mind that was in Christ; are equally needful for all the servants of the Lord, whatever may be their work.And David said to Saul, let no man's heart fail because of him,.... The Philistine, though so gigantic, mighty, and blustering: this he said within himself, so Kimchi; as David perceived the hearts of most, if not all, did, since none dared to go out and fight him, but on the contrary fled from him:

thy servant will go and fight with this Philistine; and therefore there need be no thought, care, or concern to look out for another man.