Mark 11:23-24

23 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.
24 Therefore I say to you, whatever things you ask when you pray, believe that you receive them, and you will have them.

Mark 11:23-24 In-Context

21 And Peter, remembering, said to Him, "Rabbi, look! The fig tree which You cursed has withered away."
22 So Jesus answered and said to them, "Have faith in God.
23 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.
24 Therefore I say to you, whatever things you ask when you pray, believe that you receive them, and you will have them.
25 "And whenever you stand praying, if you have anything against anyone, forgive him, that your Father in heaven may also forgive you your trespasses.
26 But if you do not forgive, neither will your Father in heaven forgive your trespasses."
Scripture taken from the New King James Version. Copyright © 1982 by Thomas Nelson, Inc. Used by permission. All rights reserved.