N.J. Stat. § 46:9-2: Covenant of seizin and warranty

A covenant in any mortgage in the words, "That the mortgagor warrants the title to the premises" shall be construed to have the same force and effect as the following words: That he covenants with the said mortgagee that he is seized of an indefeasible estate in fee simple in said premises, and will warrant and forever defend the title thereof unto the said mortgagee, his executors, administrators, successors and assigns, against all lawful claims whatsoever.