Bede

And he chose for himself five smooth stones from the brook, etc. Having shown the rejection of the preceding commandment, because of its weakness and unprofitableness, the Lord rather taught Himself to choose the very law, which is written in five books, to be observed spiritually, extracting it from the turbid minds of those who, having a veil over their hearts, could not look attentively at the face of Moses, and lifting it into the free air of evangelical light. …

Commentary on Samuel ↗