Ra’avad (Avraham ben David of Posquieres, 12th century) wrote commentaries on most of the Talmud, including tractates that exist only as Mishnah. They include basic explanations as well as more involved analyses and legal conclusions, and were highly respected by other scholars. Ra’avad’s commentary on Kinnim, a tractate at the end of Kodashim (Sacrifices) that discusses complexities regarding mixed-up bird-offerings, is one of the few extant volumes of these commentaries and begins with a short poem asking God’s help in understanding and explaining the laws.