Mark 11:22-24 NIV
“Have faith in God,” Jesus answered. [23] “Truly I tell you, if anyone says to this mountain, ‘Go, throw yourself into the sea,’ and does not doubt in their heart but believes that what they say will happen, it will be done for them. [24] Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours.
This is a wonderful promise from Jesus to His redeemed people.