Aside from the New Testament, and aside from classical works that Christian copiests may have edited, there is the Talmud. All of the Talmudic references to Jesus were censored when the Talmud was printed in Christian lands, and most of the references to Jesus in the Talmud are anti-Christian polemics, but in tractate Avoda Zara, 16b:15 through 17a:3, there is a passage that (if you find an un-censored version -- the Sefaria web site has it) describes the encounter between a Rabbi Eliezer and one Ya'akov (Jacob) of Kefar Sekhania, a follower of Jesus. As a result of this encounter, Eliezer was arrested and charged with heresy (probably charged with being a Christian). This story must have taken place not too long before the Bar Kokhba revolt (the year 132), and Eliezer recounts a teaching