Because of its age and significance, the expository commentary on the book of Genesis [q.v., under Hebrew Bible] Bereshit Rabbah, commonly known in English as Genesis Rabbah, is considered to be of primary position in the Midrash, a collection of scriptural exegesis and commentary that is part of the larger body of rabbinic literature. The Talmudic literature, including the Mishnah and the Babylonian [q.v.] and Palestinian Talmuds, along with the midrashic commentaries like Genesis Rabbah, forms the primary written authority for Jewish civil and religious law.
The midrashic writings of the rabbinic literature are a collection of biblical exegesis divisible into two main categories: the Midrash Aggadah, or exegesis with a didactic or edifying purpose, and the Midrash Halakha, or exegesis with the purpose of establishing law. The word “midrash” means “to study” or “to investigate,” and it is used to signal works of expository exegesis, either didactic or legal, from different periods of time.
The midrash Genesis Rabbah is attributed by tradition to the rabbinic teacher R. Hoshaiah, who lived in Palestine during the 3rd century a.d. However, there is evidence of numerous later additions to the work, and it is probable that the text was not fixed for several centuries after its original composition. Genesis Rabbah is of primary importance in the midrashim, and the biblical commentary it includes has exerted a significant influence on subsequent exegesis and Jewish law.
In Genesis Rabbah, the text of Genesis is explicated in an unbroken sequence, verse by verse, except for the genealogies and a few repetitious passages, which are omitted. The commentary on Genesis 9:5 presented here—just a few short sentences—is of signal importance in Jewish theology and law because it “creatively,” as Noam Zohar puts it, finds in this passage the basis for the prohibition of suicide. The commentary defines suicide as a form of murder. However, the fact that the verse is prefaced by “but” or “yet”(omitted in most translations) is taken, following midrashic practice, to signify that the prohibition may also allow for exceptions applies, as in cases like that of Saul, who first asked his armor-bearer to kill him and then fell on his sword to avoid capture and torture by the Philistines, and in cases like those of Chananyah, Mishael, and Azaryah (often called by their foreign names, Shadrach, Meschach, and Abednego) in the Book of Daniel, where they choose to die in the fiery furnace rather than worship Nebuchadnezzar’s idol. No explicit reason is given for such exceptions, though the distinction may refer to the motive for choosing death, rather than the causal manner of bringing it about. Nevertheless, the passage has been of signal importance in Jewish thought, serving to differentiate martyrs from suicides; whether martyrs may actively kill themselves would later be hotly debated in medieval Judaism.
Source
Genesis Rabbah, tr. Baruch Brody. Material in introduction from Noam Zohar and Daniel J.H. Greenwood.
COMMENTARY ON GENESIS 9:5
This [prohibition of murder (in Genesis 9:5, “for your life-blood I shall demand satisfaction,”)] includes the person who strangles himself. I might think it applies in the case like that of Saul. The verse says “but.” I might think that it applies to Chananyah, Mishael, and Azaryah. The verse says “but.”