Midrasch zu Tehillim 105:38

"Egypt rejoiced at their departure" (Psalms 105:38) Rabbi Berchiah said: this can be compared to a corpulent man that was riding on a donkey. The donkey hopes, "When will he get down from me?!" and [the man] himself hopes, "When will I get off the donkey?!". When he gets down, the man rejoiced and the donkey rejoices. But I don't know who is happier. Such was it when Israel was in Egypt. The plagues were coming on the Egyptians and the Egyptians were hoping, "When will Israel go out?!" And Israel was hoping, "When will the Holy One Blessed Be He redeem us?" When they were redeemed, both these and these were happy, but we don't know who was happier. From what David said: "Egypt rejoiced at their departure", we know that Egypt was happier.