R. Benjamin b. Immanuel Mussafia (1606–1675), rabbi, philologist, physician, and author. A descendant of Spanish Marranos, he was probably born in Spain; little is known of his early years. He received a broad philosophical education, and, apart from his great talmudic scholarship, had a sound knowledge of Latin, Greek, and Arabic. He lived in Hamburg where he distinguished himself as a physician, and gained fame in the medical profession with the publication of his books on medicine. Consequently, he was invited to act as personal physician to King Christian IV of Denmark, to whom he dedicated the scientific work Mei ha-Yam (Amsterdam, 1642). When the king died in 1648, R. Mussafia moved to Amsterdam where he became a member of the well-known bet ha-midrash "Keter Torah." In his old age, he acted as one of the scholars of Amsterdam, and his signature was first on the eulogy and letter of recognition of Shabbetai Zevi, the false messiah, which was signed by Portuguese and bet ha-midrash "Keter Torah" scholars. In consequence, R. Jacob Sasportas, a zealous fighter against the Shabbateans, attacked him in his Oholei Ya'akov.

Mussafia's most important work is Musaf he-Arukh (Amsterdam, 1655), a supplement of linguistic entries to the Arukh of R. Nathan b. Jehiel of Rome, in which he also gave new explanations to Latin and Greek words in that work. In his research he based himself largely on Buxtorf's lexicon. The book gave him a world reputation as a scholar, and it was published in more than 20 editions. His commentary on the Jerusalem Talmud has not been published. His scientific works, written under the Latin pseudonym, Dionysius, include Mei Zahav (Hamburg, 1638), on the healing properties of gold; and Mei ha-Yam (Amsterdam, 1642), on the tidal flow.

עם עם קטע מהקדמת המחבר, מן ההוצאה הראשונה. קטע זה בלבד חזר ונדפס במהדורות הבאות כ"הקדמת המחבר". מנוקד. ציוני השרשים בצידי העמודים שונים מאלה שבדפוס האמבורג 1638.