I wasn't able to find your reference in Josephus; but Joseph
Fitzmyer, in his commentary on Luke in the Anchor Bible Commentary series,
has a note on "to Abraham's bososm" in vol. 2, p. 1132 of his commentary.
He mentions Echa Rabb. 1.85; Pesqita Rabb. 43 # 108b from the late
midrashim, and the Babylonian Talmud, b. Qidd. 72a-b among other sources.
I hope this helps,
David L. Moore
Miami, Florida, USA
Southeastern Spanish District of the A/G Dept. of Education
E-mail: dvdmoore@ix.netcom.com
Home Page: http://members.aol.com/dvdmoore