N.Y. Real Prop. Acts. Law § 243

§ 243. Grant of fee or freehold. A grant in fee or of a freehold\nestate, must be subscribed by the person from whom the estate or\ninterest conveyed is intended to pass, or by his lawful agent thereunto\nauthorized in writing. If not duly acknowledged before its delivery,\naccording to the provisions of this chapter, its execution and delivery\nmust be attested by at least one witness, or, if not so attested, it\ndoes not take effect as against a subsequent purchaser or incumbrancer\nuntil so acknowledged.\n