Singing the song – B’shallach
The phrase, “Moses and the Children of Israel”, indicates that Moses led the singing and the people followed or responded to him.
They couldn’t have used a written text because the song was clearly spontaneous, a lyrical upsurge that arose from the moment. The composer was Moses, inspired by God the Redeemer.
It is possible that whatever the people heard from Moses they then repeated.
How, then, were the words and phrases recorded?
In the course of the redaction of the Torah text, the immortal words of Scripture were given permanent shape and God’s mighty saving power was remembered from year to year.