Matthew 17:19-21 New King James Version (NKJV)

¹⁹ Then the disciples came to Jesus privately and said, “Why could we not cast it out?”

²⁰ So Jesus said to them, “Because of your ^[a]unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you. ^21 [b]However, this kind does not go out except by prayer and fasting.”

Mark 9:28 New King James Version (NKJV)

²⁸ And when He had come into the house, His disciples asked Him privately, “Why could we not cast it out?”

Mark 9:29 New King James Version (NKJV)

²⁹ So He said to them, “This kind can come out by nothing but prayer ^[a]and fasting.”