R. Asher ben Jehiel (1250/ 1259 – 1328) was an eminent rabbi and Talmudist best known for his abstract of Talmudic law. He is often referred to as Rabbenu Asher, “our Rabbi Asher” or by the Hebrew acronym for this title, the ROSH (literally "Head"). The Rosh was born in western Germany and died in Toledo, Spain. His family was prominent for learning and piety, his father Yechiel was a Talmudist, and one of his ancestors was Rabbi Eliezer ben Nathan (the RaABaN). Asher had eight sons, the most prominent of whom were Judah and Jacob, author of the Arba'ah Turim, a code of Jewish law. His primary teacher was the Tosafist Rabbi Meir of Rothenburg, then in Worms. In addition to his studies, Rosh worked in money lending, and according to his own statement, was independently wealthy. In 1286, Emperor Rudolf I had instituted a new persecution of the Jews, and Rabbi Meir left Germany, but was captured and imprisoned. The ROSH raised a ransom for his release, but Rabbi Meir refused it, for fear of encouraging the imprisonment of other rabbis. Thereafter Rosh assumed Rabbi Meir's position in Worms. He was, however, forced to emigrate (in all likelihood, a victim of blackmail by the government, aimed at acquiring his fortune). After leaving Germany, he first settled in southern France, and then in Toledo, Spain, where he became rabbi on the recommendation of Rabbi Solomon ben Aderet (RaShBA). Rabbenu Asher's son Judah testified to the fact that he died in poverty. Rabbenu Asher possessed "methodical and systematic" Talmudic knowledge, and was distinguished for his ability to adumbrate long Talmudic discussions. The ROSH, influenced by his teacher Rabbi Meir, was averse to lenient decisions in halakha, even when theoretically justified. (Several of his rulings which may appear lenient, are actually strictures: his decision against praying more than three times a day is, in fact, limiting. Similarly, his assertion that the phrase halacha le-Moshe me-Sinai - "an oral law revealed to Moses on Sinai" - does not always bear a literal meaning but often signifies a universally adopted custom, is not usually taken as a liberal interpretation.) The ROSH was, however, known for his independent legal reasoning: "We must not be guided in our decisions by the admiration of great men, and in the event of a law not being clearly stated in the Talmud, we are not bound to accept it, even if it be based on the works of the Geonim." (For instance, the Rosh ruled that the liturgy of the Geonim was not subject to the Talmudic rule against change in the prayers.) Rabbenu Asher was opposed to the study of secular knowledge, especially philosophy. He held that philosophy is based on critical research, whereas religion is based on tradition and the two are thus "incapable of harmonization". He said that "none that go unto her may return" - in fact, he thanked God for having saved him from its influence, and boasted of possessing no knowledge outside the Torah. He led the anti-Maimonists in Spain; he also attempted to issue a decree against the study of non-Jewish learning. One effect of this attitude was to limit his influence on secular Spanish Jewry. At the same time, within rabbinic circles, "he transplanted the strict and narrow Talmudic spirit from Germany to Spain", and this, in some measure, turned Spanish Jews from secular research to the study of the Talmud.

יש רושמי-ספרים שלא הביאו בחישוב פרט-השנה את האות י שבתיבה 'עלינו', ולדעתם נדפס הספר בשנת תע"ה. אך זו טעות. מעבר לשער הקדמת המדפיס, שלמה ב"ר יהודא ליב [ב"ק] מפראג ז"ל. נדפס מתוך כתב יד המיוחס לר' בצלאל אשכנזי, בעל "שיטה מקובצת". דף א-ו: פירוש הרא"ש על מסכת תמיד. דף ז-כז: פירוש הראב"ד על מסכת תמיד. הפירוש מיוחס לראב"ד, אולם מחברו הוא מחכמי אשכנז. עיין: חיים מיכל, אור החיים, עמ' 28; יעקב זוסמן, פירוש הראב"ד למסכת שקלים, בתוך: מאה שערים, לזכר יצחק טברסקי, ירושלים תשס"א, עמ' 147-144; עוזיאל פוקס, על כמה ממפרשי מסכת תמיד, קבץ על יד, טו (כה), ירושלים תשס"א, עמ' 115-107. דף כח,א-ל,ב: תוספות הרא"ש על פרק משוח מלחמה ופרק עגלה ערופה, במסכת סוטה. דף ל,ב-לג,א: פירוש הריטב"א על פרק חלק [בסנהדרין]. דף לג,א-[1,א]: פירוש תוספות הרא"ש על מסכתות הוריות, קינין, מידות. דף [1]: פירוש לרבינו דוד [בונפיד] לפרק ד מיתות [בסנהדרין]. הפירוש לפרק חלק, המיוחס להריטב"א, הוא של ר' דוד בונפיד. עיין: חיד"א, פתח עינים, חלק ב, ליוורנו תק"ן, דף לז, א; מיכל, אור החיים, עמ' 321. עיין גם: י"נ עפשטיין, הקדם, שנה א (תרס"ז), עמ' 131. בן יעקב ופרידברג מייחסים בטעות את הפירוש לפרק ארבע מיתות לר' דוד אופנהיים. ידועים טפסים על קלף. על החיבור ראה: א' שוחטמן, עלי ספר, ג, תשל"ז, עמ' 84-83.