An entity named aráru is repeatedly mentioned in the sacrificial formulae called stambayajús which are recited by the Adhvaryu when he prepares the altar (védi) of the New and Full Moon sacrifices. These formulae say that aráru needs to be expelled from the earth of the védi and prevented to leap to the sky. Though aráru seems a malevolent being in the ritual, old Vedic sources call it “son of an ásura”. A passage of the Atharvaveda reveals that aráru was indeed considered to be the son of Yama. aráru has thus been demonized by the later Vedic literature, in a way which evokes the fate of the daēuua in Avestic literature. The case of aráru shows that such a process of demonization was also at work within the Vedic religion itself.