Jewish Encyclopedia: Baptism: "According to rabbinical teachings, which dominated even during the existence of the Temple (Pes. viii. 8), Baptism, next to circumcision and sacrifice, was an absolutely necessary condition to be fulfilled by a proselyte to Judaism (Yeb. 46b, 47b; Ker. 9a; 'Ab. Zarah 57a; Shab. 135a; Yer. Kid. iii. 14, 64d). Circumcision, however, was much more important, and, like baptism, was called a "seal" (Schlatter, "Die Kirche Jerusalems," 1898, p. 70). But as circumcision was discarded by Christianity, and the sacrifices had ceased, Baptism remained the sole condition for initiation into religious life. The next ceremony, adopted shortly after the others, was the imposition of hands, which, it is known, was the usage of the Jews at the ordination of a rabbi. Anointing with oil, which at first also accompanied the act of Baptism, and was analogous to the anointment of priests among the Jews, was not a necessary condition."
