Tosefta תוספתא
The "supplement" to the Mishnah: the same order of sedarim and tractates, but three times the text—and often the very explanation the Mishnah lacks.
The Tosefta is built like the Mishnah: the same six orders, the same tractates, almost the same chapters. But where the Mishnah says a single line, the Tosefta gives a dispute, a case and an explanation. The Talmud constantly cites it as a baraita—"it was taught elsewhere."
Who compiled it is not known for certain; the Talmud connects such collections with Rabbi Chiya and Rabbi Oshaya, disciples of Rabbi Yehuda haNasi. The Tosefta did not become law in its own right: where it differs from the Mishnah, the Mishnah is followed. But without it many a mishnah is simply unintelligible.
On the timeline
Related
Sources
Chazal: Mishnah, Talmud, midrash, Zohar
- Chullin 141a — the baraitot of Rabbi Chiya and Rabbi Oshaya
Rishonim
- Rambam, introduction to the Mishneh Torah — the place of the Tosefta among the books of the Oral Torah
Basis: documents and evidence.