“The Book of God's Wars?"By Rabbi Jack Abramowitz
The Jews traveled until they eventually settled on the border of Moab. From there, G-d took them to a well, where G-d said He would them water. The Jews sang a song of praise at this. From there, they traveled on.
Most striking about this aliyah is a quote attributed to “The Book of G-d’s Wars” (“Sefer Milchamos Hashem”). While some commentators assume this to be a reference to some part of the Torah, most assume it to be an ancient book, now lost. It should not surprise us that the Torah quotes another book; it quotes the dialogue of humans all the time! In fact, more than a entire chapter of the Book of Daniel is dedicated to relating a letter written by Nebuchadnezzar. Other books of Kesuvim (the Writings) similarly recount correspondence, historical records, etc. So, in the big picture, this is not as unusual as one might first suspect.