Mark 11:22:

And Jesus answering saith unto them, Have faith in God.

See also:

You Have Faith
Faith in Your Faith vs. Faith in God
What Mark 11:22 Really Means
What Galatians 2:20 Really Means
Speaking to Mountains, Trees and Diseases
Healing and Correct Doctrine
Does Mark 11:23 Work for Unbelievers?
How Can I Get Rid of Unbelief?
Should I Have Faith in My Faith?
Does God Use Faith?
Objection: Faith Must Be IN GOD (Mark 11:22), So It Is Not Something You Can Use Yourself to Change Things
Objection: Mark 11:23 Is Just an Expansion of Mark 11:22 About Trusting IN GOD
Objection: Occult Practitioners Attempt to Confess Things into Existence and Speak to Material Things to Make Them Change
Mistake: Fear
Notes on Matthew 21:18-22
Notes on Mark 11:23-24