Matthew 17:20

and Jesus says to them, On account of your unbelief. For truly I say unto you, If you have faith as a grain of mustard seed, you will say to this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible to you.

Luke 17:6

And the Lord said, If you have faith as a grain of mustard seed. you should say to this sycamine tree, Be thou plucked up, and planted in the sea; and it would obey you.

Matthew 13:31

And He submitted another parable to them, saying; The kingdom of the heavens is like unto a grain of mustard seed, which, a man having taken, sowed in his field;

Matthew 21:21

And Jesus responding said to them, Truly I say unto you, if you may have faith, and doubt not, not only shall you do that of the fig-tree, but you shall say to this mountain, Be thou taken up and cast into the sea, and it will be done.

Mark 11:23

Truly I say unto you, That whosoever may say to this mountain, Be thou taken up and cast into the sea; and may not doubt in his heart, but believe that what he says does take place; it shall be unto him.

1 Corinthians 13:2

And if I have the gift of prophecy, and understand all mysteries, and all knowledge; and if I have all faith, so as to remove mountains, and have not divine love, I am nothing.

Mark 9:23

And Jesus said to him, It is this, if you are able (to believe); all things are possible to him that believeth.

Matthew 14:30-31

And seeing the wind strong, became alarmed; and beginning to sink, he cried out, saying, Lord, save me.

Matthew 17:9

And they coming down from the mountain, Jesus charged them, saying, Tell the vision to no one, until the Son of man may rise from the dead.

Matthew 17:17

And Jesus responding said: O, faithless and perverse generation, how long shall I be with you? bring him hither to me.

Mark 4:31

Tis like a grain of mustard seed, which when it may be sown upon the earth, is the smallest of all seeds which are upon the earth,

Luke 1:37

Because no word shall be impossible with God.

Luke 18:27

And He said, Those things which are impossible with men are possible with God.

John 11:40

Jesus says to her; Did I not tell thee, that, if thou canst believe, thou shalt see the glory of God?

Hebrews 3:19

And we see that they were not able to enter in on account of their unbelief.

Treasury of Scripture Knowledge

Summary

And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.

Bible References

Because

Matthew 17:17
And Jesus responding said: O, faithless and perverse generation, how long shall I be with you? bring him hither to me.
Matthew 14:30
And seeing the wind strong, became alarmed; and beginning to sink, he cried out, saying, Lord, save me.
Hebrews 3:19
And we see that they were not able to enter in on account of their unbelief.

A grain

Matthew 13:31
And He submitted another parable to them, saying; The kingdom of the heavens is like unto a grain of mustard seed, which, a man having taken, sowed in his field;
Mark 4:31
Tis like a grain of mustard seed, which when it may be sown upon the earth, is the smallest of all seeds which are upon the earth,

Nothing

Mark 9:23
And Jesus said to him, It is this, if you are able (to believe); all things are possible to him that believeth.
Luke 1:37
Because no word shall be impossible with God.
Luke 18:27
And He said, Those things which are impossible with men are possible with God.