Bereshith Rabba, chap. 95.

The masters of the Kabbalah, of blessed memory, say that Abraham’s
Rabbi, i.e., teacher, was the angel Zadkiel.

Rabbi Menachem’s comment on the Pent., Exod. iii. 5.

Adam’s book, which contained celestial mysteries and holy wisdom, came down as an heirloom into the hands of Abraham, and he by means of it was able to see the glory of his Lord.

Zohar Parashah Bereshith.

Abraham was the author of a treatise on the subject of different kinds of witchcraft and its unholy workings and fruits, as also of the Book of Creation, through holy names (by means of which, namely, anything could be created).

Nishmath Chayim, chap. 29.

The whole world once believed that the souls of men were perishable, and that man had no pre-eminence above a beast, till Abraham came and preached the doctrine of immortality and transmigration.

Ibid., fol. 171, col. 1.

A good son delivers his father from the punishment of hell, for thus we find that Abraham our father delivered Terah, as it is said in Gen. xv. 15, “And thou shalt go to thy fathers in peace.”  This implies that God had communicated to him the tidings that his father had a portion in the world to come and was now “in peace” there.

Pesikta Zotarta, fol. 3, col. 2.

Before Abraham was circumcised God spake to him in the Chaldee language, that the angels should not understand it. (This is proved from Gen. xv. 1.)

Yalkut Chadash, fol. 117.

Rabbi Levi said Abraham sits at the gate of hell and does not permit any circumcised Israelite to enter.  But if any appear who happen to have sinned unduly, these he (by an indescribable contrivance) causes to become uncircumcised and lets pass without scruple into the region of torment; and this is what is said in Ps. lv. 20, “He hath put forth his hands against such as be at peace with him:  he hath broken his covenant.”

Yalkut Shimoni, fol. 33, col. 2, sec. 18.

Abraham was circumcised on the Day of Atonement, and God looks that day annually on the blood of the covenant of our father Abraham’s circumcision as atoning for all our iniquities, as it is said in Lev. xvi. 30, “For on that day shall he make an atonement for you, to cleanse you from all your sins.”

Yalkut Chadash, fol. 121, col. 1, sec. 3.

“And it came to pass that when Abram was come into Egypt” (Gen. xii. 14).  And where was Sarah?  He confined her in a chest, into which he locked her, lest any one should gaze on her beauty.  When he came to the receipt of custom, he was summoned to open the chest, but declined, and offered payment of the duty.  The officers said, “Thou carriest garments;” and he offered duty for garments.  “Nay, it is gold thou carriest;” and he offered the impost laid on gold.  Then they said, “It is costly silks, belike pearls, thou concealest;” and he offered the custom on such articles.  At length the Egyptian officers insisted, and he opened the box.  And when he did so, all the land of Egypt was illumined by her beauty.