Genesis Rabbah (Hebrew: בְּרֵאשִׁית רַבָּה, romanized: Bərēšīṯ Rabbā) is a religious text from Judaism's classical period, probably written between 300 and 500 CE with some later additions.
It is an expository midrash to the first book of the Torah, assigned by tradition to the amora Hoshaiah Rabbah, who flourished in the third century in Roman-ruled Syria Palaestina.
Genesis Rabbah contains many simple explanations of words and sentences, often in Middle Aramaic, suitable for instructing youth.
The editor of the midrash has strung together various longer or shorter explanations and aggadic interpretations of the successive passages, sometimes anonymously, sometimes citing the author.
The editor adds to the running commentary longer aggadic disquisitions or narratives, connected in some way with the verse in question or with one of the explanations of it—a method not unusual in the Talmud and other midrashim.
The first chapters of Genesis, on the creation of the world and man, furnished especially rich material for this mode of exegesis.
With few exceptions, it is introduced by one or more prefatory remarks starting from a verse taken from another Biblical passage as text, generally from the Ketuvim.
About 70 are cited with the name of the Rabbi with whom they originated or whose explanation of the verse in question was used to introduce the section of the Genesis Rabbah.
The single prefaces, of which there is a large number, contain explanations of their text which refer entirely or in its last part to the verse or passage of Genesis to be expounded in that section.
Far more difficult than any question concerning the outward form of Genesis Rabbah is that of deciding how much of its present contents is original material included in it, and how much of later addition.
The tradition that Rabbi Hosha'iah is the author of Genesis Rabbah may be taken to mean that he began the work, in the form of the running commentary customary in tannaitic times, arranging the exposition on Genesis according to the sequence of the verses, and furnishing the necessary complement to the tannaitic midrashim on the other books of the Torah.
The present Genesis Rabbah shows a singular disproportion between the length of the first Torah portion and that of the eleven others.
Thus, beginning with the Torah portion Vayishlach, extensive passages are found that bear the marks of the later aggadah, and have points of connection with the Tanhuma homilies.
The passages were probably added at an early date, since they are not entirely missing in the older manuscripts, which are free from many other additions and glosses that are found in the present editions.