Avraham as source of magic

 Zohar (1:133b)  BUT UNTO THE SONS OF THE CONCUBINES THAT ABRAHAM HAD ABRAHAM GAVE GIFTS  What sort of gifts were they? They comprised the sides of the low grades, that is to say, the names of the powers of the unclean spirit, so as to complete the whole list of grades. (Isaac was raised above those grades by the power of the true faith.) “The sons of the concubines” are the sons of Keturah, who had formerly been a concubine and was now once more a concubine.’ R. Hiya said that the term “concubines” here in the plural must be taken literally. AND HE SENT THEM AWAY FROM ISAAC HIS SON , so that they should not be on a par with Isaac. WHILE HE YET LIVED , that is, while Abraham was yet alive and vigorous, so that they should not complain against him after his death, and so that Isaac might strengthen himself in the side of rigour so as to prevail over them all and make them all submit to him. EASTWARD, UNTO THE EAST COUNTRY : for the reason that there are the haunts of the impure practitioners of magic and witchcraft. Observe this. It is written: “And Solomon's wisdom excelled the wisdom of all the children of the East” (I Kings V, 10). Herein is an allusion to the descendants of the very children of Abraham's concubines, who, as already said, inhabit the mountains of the East, where they instruct the sons of men in the arts of magic and divination. It was this very land of the East from which came Laban and Beor and his son Balaam, who were all magicians.’

Rashi (Bereishis 25:6)  ABRAHAM GAVE GIFTS — Our Rabbis explained (Sanhedrin 91a) that he transmitted to them the names of impure things. 

Chizkuni() “Avraham gave substantial gifts;” Our sages (in Sanhedrin 91 understand the word מתנות as referring to the names of different types of pagan deities, ”