Mass. Gen. Laws ch. 244, § 1: Foreclosure by entry or action; continued possession

Section 1. A mortgagee may, after breach of condition of a mortgage of land, recover possession of the land mortgaged by an open and peaceable entry thereon, if not opposed by the mortgagor or other person claiming it, or by action under this chapter; and possession so obtained, if continued peaceably for three years from the date of recording of the memorandum or certificate as provided in section two, shall forever foreclose the right of redemption.