On that day R’ Akiva expounded: Then Moses and the children of Israel sang this song to HASHEM, and they spoke saying (Exodus 15:1). There is no necessity [for the verse] to say, “saying”; what [then] is meant by “saying”? It teaches that the Is-raelites responded to Moses after each phrase, as when they recite the Hallel; therefore it says, “saying.” R’ Nechemiah says: As when they recite the Shema, and not as when they recite the Hallel.