Rabbeinu Yehonasan was born in Provence, Southern France to his father Reb David. He was considered the leader of the “Chachmei Lunel” and was a disciple and colleague of the Raava”d1.
He was a big admirer of the Ramba”m and it is reported that he sent a pamphlet to the Ramba”m containing 24 areas in the Rambam’s Yad Hachazaka that needed clarification. This pamphlet was sent on behalf of the entire body of the “Chachmei Lunel”1. The Ramba”m was glad that his work was being studied so seriously and responded to their requests1.
When news of the the Rambam’s Sefer Moreh Nevuchim reached Provence, Rabbeinu Yehonasan wrote to Rambam, beseeching him to send a translated copy over to Provence. The Rambam acceded to his request but regrettably informed Reb Yehonasan that he was unable to issue a translation and so the Sefer reached Provence in its original Arabic1,2. Reb Yehonasan then tasked Rebbi Yehuda Ibn Tibbon to translate this work into Hebrew1,2.
He authored a commentary on the Rif’s Sefer HaHalachos spanning numerous Masechtot but only his work on Masechet Eruvin has been incorporated in the standard Shas1. However, the Chid”a mentions that he saw a manuscript of Reb Yehonasan’s work on Masechet Bava Metzia3. Recently, his works on other tractates have been found and printed as individual Sefarim1. His commentary to Masechet Chulin can be found on HebrewBooks.org and was published around 200 years ago and named Avodat Haleviim.
He is also thought to have authored numerous Halachic Teshuvot3 as well as a Torah commentary by the name of Naaseh Venishma4.
Not much at all is known about his family. We have a tradition that at the end of his life he wished to emigrate to Eretz Yisrael1. He sent a number of letters with Halachic queries to Ritzb”a who resided in the North of the country on the topic of Mitzvot that are (only) applicable in Eretz Yisrael2. He eventually did ascend to the Holy Land and visited Jerusalem. He passed away in Eretz Yisrael1. Some say that he emigrated together with 300 Baalei HaTosfot and that this was in the year 12111. Others place the year of his death as the same year the Ramba”m passed away; 12045. It is questionable if this can be reconciled with the above tradition.
1. The Rishonim, 2006, ArtScroll.
2. שמות חכמים, הרב אברהם מאיר וייס, תשס"ט
3. שם הגדולים להחיד"א זצוק"ל
4. קונטרס מבוא השערים, הרב מרדכי צבי פויגעל, תשמ"ג
5. קורא הדורות, הרב דוד קונפורטי זצוק"ל