What is the source for Yosef's coat being a "coat of many colors"? Is there a particular commentator that translates פַּסִּים as colorful?
Genesis 37:3
וְיִשְׂרָאֵ֗ל אָהַ֤ב אֶת־יוֹסֵף֙ מִכׇּל־בָּנָ֔יו כִּֽי־בֶן־זְקֻנִ֥ים ה֖וּא ל֑וֹ וְעָ֥שָׂה ל֖וֹ כְּתֹ֥נֶת פַּסִּֽים׃
Now Israel loved Joseph best of all his sons, for he was the child of his old age; and he had made him an ornamented tunic
https://www.sefaria.org/Genesis.37.3?lang=bi&with=all&lang2=en
The Jewish Action article mentioned by @dov (thank you) contains the following paragraph:
The earliest mention of the ketonet passim being a variegated garment dates back to the third-century bce Greek Septuagint, which translates it as χιτῶνα ποικίλον (poikilos)—a cloak of various colors. (In II Samuel it translates the same word differently: karpótos.) Following the Septuagint, the fourth-century Latin Vulgate translates ketonet passim as “tunicam polymitam”—a tunic woven with many threads, usually taken to mean different colored threads. The early seventeenth-century English King James Bible calls it a “coat of many colours.” Possibly based on this, the once standard Jewish English translation, the 1917 Jewish Publication Society (JPS) Tanakh, calls it “a coat of many colors.” Some traditional commentaries adopted this interpretation. The influential eleventh-century Hebrew grammarian Jonah ibn Janach (Sefer HaShorashim, entry “pas” [p. 405]) assumes “passim” is the plural of “pas,” and based on Daniel and the Targum to Kings, “pas” is a handbreadth; thus, the ketonet passim was a silk garment in which each handspan was a different color. Radak (1160-1235; Provence), based on Daniel, derives that the garment was made of stripes of various colors. Ralbag (II Samuel 13:18) says that each handspan of the garment was a different color, and it included many colors.
So the well-known commentators who subscribe to the colours idea are the Radak and the Ralbag.
