Mark 11:23-26

I tell you the truth, you can say to this mountain, ‘Go, fall into the sea.’ And if you have no doubts in your mind and believe that what you say will happen, God will do it for you. So I tell you to believe that you have received the things you ask for in prayer, and God will give them to you. When you are praying, if you are angry with someone, forgive him so that your Father in heaven will also forgive your sins. [But if you don’t forgive other people, then your Father in heaven will not forgive your sins.]”