Matthew 17:21 “Howbeit this kind goeth not out but by prayer and fasting.”
This verse is genuine Scripture, even though it is questioned by many critics. The verse is found in a great host of Greek manuscripts (including the Alexandrian manuscript “A,”), is in several early versions, and is quoted by several early church fathers. It is missing in only three Greek manuscripts (“B,” Aleph, and 33). Edward Miller, a very learned Bible manuscript scholar, called the omission of the verse from some new English translations, “a servile submission to ‘B,’ the Vatican manuscript.” The verse is also found in the Gospel of Mark, so it is certain that it is genuine Scripture. Furthermore, it is true that some works that we are called to do require serious prayer, even fasting, if we are to see victory.