Jubilees 48:15
14 And all the peoples whom he brought to pursue after Israel, the Lord our God cast them into the midst of the sea, into the depths of the abyss beneath the children of Israel, even as the people of Egypt had cast their children into the river He took vengeance on 1,000,000 of them, and one thousand strong and energetic men were destroyed on account of one suckling of the children of thy people which they had thrown into the river. 15 And on the fourteenth day and on the fifteenth and on the sixteenth and on the seventeenth and on the eighteenth the prince Mastêmâ was bound and imprisoned behind the children of Israel that he might not accuse them. 16 And on the nineteenth we let them loose that they might help the Egyptians and pursue the children of Israel.
Jubilees 49:2
1 Remember the commandment which the Lord commanded thee concerning the passover, that thou shouldst celebrate it in its season on the fourteenth of the first month, that thou shouldst kill it before it is evening, and that they should eat it by night on the evening of the fifteenth from the time of the setting of the sun. 2 For on this night -the beginning of the festival and the beginning of the joy- ye were eating the passover in Egypt, when all the powers of Mastêmâ had been let loose to slay all the first-born in the land of Egypt, from the first-born of Pharaoh to the first-born of the captive maid-servant in the mill, and to the cattle. 3 And this is the sign which the Lord gave them: Into every house on the lintels of which they saw the blood of a lamb of the first year, into (that) house they should not enter to slay, but should pass by (it), that all those should be saved that were in the house because the sign of the blood was on its lintels.
Notes and References
"... As often in the book, the narrator speaks of the role of “the angel Mastema,” the Satan-like figure who leads the forces of evil. Here, Mastema tries to kill Moses, then, failing that, seeks to aid Pharaoh’s magicians in combating the ten plagues, and still later urges the Egyptians to pursue the departing Israelites - in short, Mastema does everything he can to foil God’s plan to free the Israelites. He actually has to be held in restraints for five days, “bound and locked up” (Jubilees 48:15), to prevent him from succeeding. By contrast, in chapter 49 - largely taken up with detailing the laws of Passover and full of the “terminology of the Heavenly Tablets”—the narrator suddenly reminds Moses of what happened on the fateful night that inaugurated the exodus ... Here, there is a clear about-face: instead of trying to frustrate God’s plans, Mastema’s legions actually become God’s agents, carrying out the tenth plague instead of opposing it ..."
Kugel, James L. A Walk through Jubilees: Studies in the Book of Jubilees and the World of Its Creation (p. 229) Brill, 2012