Matthew 21:21
And Jesus answered them: truly, I say to you, if you have faith and do not doubt, you will not only do what has been done to the fig tree, but even if you say to this mountain, be taken up and cast into the sea, it will happen. The faith without doubt that moves mountains is the teaching that Matthew 17:20 established (mustard-seed faith moves mountains) now applied to the disciples who witnessed the fig tree. The mountain that can be cast into the sea is the mountain before them — possibly the Mount of Olives, whose overthrow was associated with the messianic age in Zechariah 14:4.