S1 is one of the names of the Sassoon Codex, one of the oldest biblical codex. This precious object made of sheepskin and ink was just bought at Soetheby’s for some $38,000,000 by a purchaser acting on behalf of the Museum of the Jewish People (formerly Beit Ha’tefuztot) in Tel Aviv. The story of the sale, reported here, of this very old Bible, from Syria or the Land of Israel, dating back to the 10^th century, is itself an icon of modern Judaism. It’s about a lot of things all together: the codex itself, the Sassoon family and modern Sephardi history, migration and global Judaism, enormous wealth and culture, opioids and British empire, fine Judaica, the history of precious objects, the State of Israel and cultural nationalism. As for the Sassoon family, the prominent line of the family fled Baghdad in the 1830s, relocated to Mumbai, set up shop in Shanghai and London, where the family became prominent in English society and where the family history effectively ends in the middle of the 20^th century. The Sassoons are themselves the subject of a recently published family biography, written by a Sassoon, and of an exhibition at the Jewish Museum in New York City.

From here at Wikpedia, there is little bit about the modern provenance of the object: “[T]he codex resurfaced when David Solomon Sassoon purchased it for £350 in 1929 and added his bookplate to the inner binding of the manuscript.  Though known to scholars in the 20th century, the book stayed under private ownership. It was owned by D.S. Sassoon’s descendants until 1978, when they sold it to the British Rail Pension Fund through Sotheby’s Zurich. S1 was exhibited just once, in 1982 at the British Museum.^[ The manuscript was auctioned again through Sotheby’s on December 5, 1989, when it sold to a dealer for £2,035,000, who sold it to investor Jacqui Safra that same year. It was sold at Sotheby’s in New York on May 2023, for $38.1 million. The codex was on display prior to auction in London, ANY-Museum of the Jewish People in in Tel Aviv., Bridwell Library at Southern Mehodist University in Dallas, Los Angels, and New York. It was purchased by the American Friends of ANU — Museum of the Jewish People in Tel Aviv with the aid of a donation from Alfred H. Moses. This marks it as the fourth most expensive book and manuscript ever sold.” 

About the codex, apparently a sloppy job, I found this detail at the same Wikipedia page: Codex S1 (or M^S1; formerly Codex Sassoon 1053 and also Safra, JUD 002) is a Masoretic codex comprising all 24 books of the Hebrew Bible, dated to the 10th century. It is considered as old as the Aleppo Codex and a century older than the Leningrad Codex (1006), the earliest known complete Hebrew Bible manuscript.^[1] Alternatively, it might be dated to the late 9th century. The Aleppo Codex was missing 40% of its leaves when it resurfaced in Israel in 1958, while in Codex S1 12 leaves are completely missing and hundreds more are partially lost. The scribe of S1 was unusually sloppy, frequently forgetting punctuation, diacritical marks, and vowels; he also errs in his consonantal spelling on dozens of occasions