“ties up.” The Greek word translated “ties up” is the common word deō (#1210 δέω), which means to bind or tie up. However, here it has a special meaning. The word was used in magic and spells for binding someone via a spell. The word was used “to describe the ‘binding’ power of curses” (Moulton and Milligan, Vocabulary of the Greek NT). The context is the casting out of demons (v. 28), so the “binding” in this verse refers to binding a demon and making it powerless by the power of God.