'A figure known as "the satan" first appears in the Tanakh as a heavenly prosecutor, a member of the sons of God subordinate to Yahweh, who prosecutes the nation of Judah in the heavenly court and tests the loyalty of Yahweh's followers by forcing them to suffer. During the intertestamental period, possibly due to influence from the Zoroastrian figure of Angra Mainyu, the satan developed into a malevolent entity with abhorrent qualities in dualistic opposition to God. In the apocryphal Book of Jubilees, Yahweh grants the satan (referred to as Mastema) authority over a group of fallen angels to tempt humans to sin and punish them.'' - Wiki.