Midrasch zu Bereschit 4:11

In what merit were they (the Egyptians) granted burial? In the merit of his saying (Exodus 9:27) "The L rd is the righteous one (and I and my people are the wicked ones"), the Holy One Blessed be He said: If you have vindicated the L rd's judgment of You, I shall not withhold your reward and I will give you a place of burial, viz. "You inclined Your right hand — the earth swallowed them up." Variantly: "You inclined Your right hand": We are hereby apprised that He cast them to the dry land, and the dry land cast them to the sea, saying: If for only accepting the blood of Hevel, one man, it was said to me (Genesis 4:11) "Cursed are you, etc.", how will I be able to accept the blood of all of these hordes!" — until the Holy One Blessed be He said to it: (I swear that) I will not hold you responsible, as it is written "You inclined Your right hand — the earth swallowed them up," "Your right hand" connoting an oath, viz. (Isaiah 62:8) "The L rd has sworn by His right hand."