James 1:6

but let him be fully persuaded of the lawfulness of what he asks: for he that is diffident about that, is like the waves that fluctuate with the wind.

Ephesians 4:14

that we should be no longer children, fluctuating, and carried about with every empty doctrine, by men vers'd in sleight and the crafty arts of deceit:

Matthew 21:21-22

Jesus answered them, I declare to you, if ye have a full assurance of faith, ye shall not only be able to do this to a fig-tree, but if ye should even say to this mountain, be thou removed, and cast into the sea; it should be done.

Mark 11:22-24

but Jesus replied, and said to them, rely upon God.

1 Timothy 2:8

I direct therefore that the men pray in publick and private, lifting up their hands to heaven with innocence, charity, and composure.

Hebrews 10:23

Let us stedfastly maintain the hope which we have avow'd, since he is faithful that has promised:

Hebrews 11:6

now without faith it is impossible to be acceptable to him: for he that presents himself to God, cannot but believe he exists, and that he is a rewarder of those who make their addresses to him.

Hebrews 13:9

for the mind is better improv'd by the gospel-dispensation, than by the distinctions about meats, in which some have been so uselesly vers'd.

2 Peter 2:17

These are wells without water; clouds agitated with a tempest, who are consigned to the obscurity of eternal darkness.

Jude 1:12-13

they are a disgrace to your love-feasts, they indulge themselves at your festivals without reserve: clouds without water, transported with every wind: trees whose fruit soon withers and is useless, twice dead and rooted up:

Treasury of Scripture Knowledge

Summary

But let him ask in faith, nothing wavering. For he that wavereth is like a wave of the sea driven with the wind and tossed.

Bible References

Let

Matthew 21:22
and whatever ye shall ask in prayer, with faith, ye shall receive.
Mark 11:22
but Jesus replied, and said to them, rely upon God.
1 Timothy 2:8
I direct therefore that the men pray in publick and private, lifting up their hands to heaven with innocence, charity, and composure.
Hebrews 11:6
now without faith it is impossible to be acceptable to him: for he that presents himself to God, cannot but believe he exists, and that he is a rewarder of those who make their addresses to him.

He

Ephesians 4:14
that we should be no longer children, fluctuating, and carried about with every empty doctrine, by men vers'd in sleight and the crafty arts of deceit:
Hebrews 10:23
Let us stedfastly maintain the hope which we have avow'd, since he is faithful that has promised:
Hebrews 13:9
for the mind is better improv'd by the gospel-dispensation, than by the distinctions about meats, in which some have been so uselesly vers'd.
2 Peter 2:17
These are wells without water; clouds agitated with a tempest, who are consigned to the obscurity of eternal darkness.
Jude 1:12
they are a disgrace to your love-feasts, they indulge themselves at your festivals without reserve: clouds without water, transported with every wind: trees whose fruit soon withers and is useless, twice dead and rooted up: