Sforno on Exodus 14:30/ספורנו על שמות י״ד:ל׳

1ויושע ה' ביום ההוא את ישראל, by the death of those who had cruelly abused them. Those who had previously been in bondage to the Egyptians were now free. Until the Egyptians died they had been comparable to slaves running away from their masters.