Wherefore it is said in the {e} book of the wars of the LORD, What he did in the Red sea, and in the brooks of Arnon,

(e) Which seems to be the book of the Judges, or as some think, a book which is lost.

Wesley's Notes

21:14 The book of the wars of the Lord - This seems to have been some poem or narration of the wars and victories of the Lord, either by: or relating to the Israelites: which may be asserted without any prejudice to the integrity of the holy scripture, because this book doth not appear to have been written by a prophet, er to be designed for a part of the canon, which yet Moses might quote, as St. Paul doth some of the heathen poets. And as St. Luke assures us, that many did write an history of the things done, and said by Christ, Luke 1:1, whose writings were never received as canonical, the like may be conceived concerning this and some few other books mentioned in the old testament. The brooks - The brook, the plural number for the singular, as the plural number rivers is used concerning Jordan, Psa 74:15, and concerning Tigris, Nah 2:6, and concerning Euphrates, Psa 137:1, all which may be to called because of the several little streams into which they were divided.

King James Translators' Notes

What...: or, Vaheb in Suphah

Jamieson-Fausset-Brown Bible Commentary

14. book of the wars of the Lord-A fragment or passage is here quoted from a poem or history of the wars of the Israelites, principally with a view to decide the position of Arnon.

Matthew Henry's Concise Commentary

21:10-20 We have here the removes of the children of Israel, till they came to the plains of Moab, from whence they passed over Jordan into Canaan. The end of their pilgrimage was near. They set forward. It were well if we did thus; and the nearer we come to heaven, were so much the more active and abundant in the work of the Lord. The wonderful success God granted to his people, is here spoken of, and, among the rest, their actions on the river Arnon, at Vaheb in Suphah, and other places on that river. In every stage of our lives, nay, in every step, we should notice what God has wrought for us; what he did at such a time, and what in such a place, ought to be distinctly remembered. God blessed his people with a supply of water. When we come to heaven, we shall remove to the well of life, the fountain of living waters. They received it with joy and thankfulness, which made the mercy doubly sweet. With joy must we draw water out of the wells of salvation, Isa 12:3. As the brazen serpent was a figure of Christ, who is lifted up for our cure, so is this well a figure of the Spirit, who is poured forth for our comfort, and from whom flow to us rivers of living waters, Joh 7:38,39. Does this well spring up in our souls? If so, we should take the comfort to ourselves, and give the glory to God. God promised to give water, but they must open the ground. God's favours must be expected in the use of such means as are within our power, but still the power is only of God.