And we need to explain his words, because truly it was not an opportune time to sing, as we find in the Midrash (Yalkut Shimoni Divrei HaYamim II, remez 1085): "The ministering angels sought to sing a song, but the Holy One, Blessed be He, said, 'The works of My hands are drowning in the sea, and you want to sing a song before Me?'" What changed for Israel to merit singing a song? It is because when one is aroused with a strong desire to sing, the arousal does not return empty-handed. Therefore, even the simplest of the simple, and even the maidservant, merited to sing a song, something that the angels did not merit. And how exalted was this arousal, when the sea was before them, the enemy behind them, and there was no way to be saved, and yet they sang to Hashem out of a feeling of closeness and devotion.

And how fitting according to our words is the interpretation of the Chidushei HaRim on the verse 'Az Yashir,' which is stated in the future tense, because that strong feeling of arousal to sing a song, our forefathers instilled in all generations, so that they too could sing the song with great arousal, and his interpretation fits well with our words.