The Mekhilta of Rabbi Shimon ben Yochai (Jewish Babylonian Aramaic: מכילתא דרבי שמעון בן יוחאי, romanized: Mǝkhilta dǝ-Rabbi Shimʿon ben Yoḥai) is midrash halakha on the Book of Exodus from the school of Rabbi Akiva attributed to Shimon bar Yochai.
Until the early 1900s, aside from these quotations and some given by certain authors of the 16th century (such as Elijah Mizrahi in his Sefer ha-Mizrachi, Shem-Ṭob ben Abraham in his Migdal Oz, and R. Meir ibn Gabbai in his Tola'at Ya'akov[8][full citation needed]), the only known extract of any length from Mekhilta de-Rabbi Shimon was the one published by R. Isaac Elijah Landau from a manuscript of R. Abraham Halami, as an appendix to his edition of the Mekhilta.
The Mekhilta de-Rabbi Shimon had disappeared, but some extracts from it were preserved in the collection known as Midrash haGadol, as Israel Lewy first pointed out.
[23] This Mekhilta compiled from Midrash haGadol preserves abundant material from the earliest Scriptural commentaries, quoting, for instance, a sentence from the Doreshei Reshumot on Exodus 21:12[24] which is found nowhere else.
[26] A critical version, using newly discovered fragments of texts, was later published by Yaakov Nahum Epstein and his student Ezra Zion Melamed.
[27] The publication is an attempt to reconstruct the original Mekhilta of Rabbi Shimon ben Yochai, based on all extant sources.