My copy of the much anticipated Old Testament Pseudepigrapha: More Noncanonical Scriptures came in the mail this week. The book is a buffet of fascinating texts, but I was especially excited to see Martha Himmelfarb's introduction and translation of Midrash Vayissa'u (or Wayiaasa'u) (143-159). This is a text I have been working with in my thesis research and I have been startled that more English language scholarship has not been devoted to it. I am hoping that Himmelfarb's contribution encourages further research on this fascinating work. Her translation of the war with the Ninevites is particularly important, as this tradition has been largely overlooked.
Midrash Vayissa'u is familiar to students of both the Testament of Judah and the Book of Jubilees, since it preserves traditions about Jacob and his sons' wars with the Amorites and the Edomites that parallel the accounts in these two earlier works. While I do not think we can rule out some form of influence by Jubilees or the Testament of Judah on this medieval composition (I think this influence was indirect), it seems to be primarily dependent on sources/traditions that it shares in common with Jubilees and the Testament. This means that despite its later date it can give us insights into texts and traditions that existed in the Hellenistic period, making it interesting not only for those who study medieval Jewish literature, but students of Second Temple Judaism as well.
If extracanonical traditions about wars between the Israelite ancestors and their neighbors is something you find interesting, then give Midrash Vayissa'u a read. Himmelfarb's introduction and translation are now the best place to start, and if you are interested in digging further you might check out some of these sources as well.
A PDF of Lauterbach's edition of the Hebrew text, including handwritten notes, is available here.
Harm W. Hollander and Marinus de Jonge, The Testaments of the Twelve Patriarchs: A Commentary, 451-456. Another English translation of Midrash Wayissa'u. There is also translation and commentary on Testament of Judah's version earlier in the volume.
Gaston's introduction to and translation of the text in the Chronicle of Jehrameel.
English translations and introductions to the Testament of Judah and Jubilees can be found in Charlesworth's Old Testament Pseudepigrapha.
A critical Greek text of Testament of Judah can be found in Marinus de Jonge's The Testaments of the Twelve Patriarchs: A Critical Edition of the Greek Text.
James C. VanderKam's critical edition has the versional texts and English translation of Jubilees.