Matthew 17v18-21

Heavenly father
give us grace today to rebuke evil 

¹⁸ Jesus rebuked the demon, and it went out of him, and the boy was cured from that hour.
¹⁹ Then the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?”
²⁰ He said to them, “Because of your unbelief.
For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain,
‘Move from here to there,’ and it will move; and nothing will be impossible for you. 
²¹ But this kind doesn’t go out except by prayer and fasting.”