Jesus answered and said to them, “Have faith in God.” Mark 11:23

Now in the morning, as they passed by, they saw the fig tree dried up from the roots. And Peter, remembering, said to Him, “Rabbi, look! The fig tree which You cursed has withered away.” So Jesus answered and said to them, “Have faith in God. For  assuredly, I say to you, whoever says to this mountain, ‘Be removed and be cast into the sea,’ and does not doubt in his heart, but believes that those things he says will be done, he will have whatever he says. Therefore I say to you,  whatever things you ask when you pray, believe that you receive them, and you will have them. “And whenever you stand praying,  if you have anything against anyone, forgive him, that your Father in heaven may also forgive you your trespasses. But  if you do not forgive, neither will your Father in heaven forgive your trespasses.” Then they came again to Jerusalem. And as He was walking in the temple, the chief priests, the scribes, and the elders came to Him. And they said to Him, “By what authority are You doing these things? And who gave You this authority to do these things?” But Jesus answered and said to them, “I also will ask you one question; then answer Me, and I will tell you by what authority I do these things: The  baptism of John—was it from heaven or from men? Answer Me.” And they reasoned among themselves, saying, “If we say, ‘From heaven,’ He will say, ‘Why then did you not believe him?’ But if we say, ‘From men’ ”—they feared the people, for all counted John to have been a prophet indeed. So they answered and said to Jesus, “We do not know.” And Jesus answered and said to them, “Neither will I tell you by what authority I do these things.”
Mark 11:20-33 - NKJV