Cassel began his career as an author with his doctor's thesis on "Die Psalmenüberschriften" (published in the "Literaturblatt des Orients," Leipzig, 1840). He received his rabbinical diploma in 1843 from Jacob Joseph Oettinger and Zecharias Frankel, but never accepted, a rabbinical position, although he possessed a decided talent for the pulpit, as may be seen from his "Sabbath-Stunden zur Belehrung und Erbauung" (Berlin, 1868), a collection of 52 homilies on the Pentateuch, originally delivered as Sabbath lectures in a school for boys.
Cassel started his career as an author with his dissertation on "The Titles of the Psalms" (published in the "Literature Review of the East," Leipzig, 1840). He received his rabbinical diploma from Jacob Joseph Oettinger and Zecharias Frankel in 1843 but declined a rabbinical position, instead showcasing his talent for preaching through works like "Sabbath Hours for Instruction and Inspiration" (Berlin, 1868), which included homilies on the Pentateuch delivered to boys at school.