1 John 5:14-15

Now this is the confidence that we have in Him, that if we ask anything according to His will, He hears us. And if we know that He hears us, whatever we ask, we know that we have the petitions that we have asked of Him.

Mark 11:23-25

For assuredly, I say to you, whoever says to this mountain, 'Be removed and be cast into the sea', and does not doubt in his heart, but believes that those things he says will be done, he will have whatever he says. Therefore I say to you, whatever things you ask when you pray, believe that you receive them, and you will have them. And when you stand praying, if you have anything against anyone, forgive him, that your Father in heaven may also forgive you your trespasses.

 James 5:15-16

And the prayer offered in faith will make the sick person well; the Lord will raise him up. If he has sinned, he will be forgiven. Therefore confess your sins to each other, and pray for each other so that you may be healed. The prayer of a righteous man is powerful and effective.

Matthew 21:21-22

So Jesus answered and said to them, "Assuredly, I say to you, if you have faith and do not doubt, you will not only do what was done to the fig tree, but also if you say to this mountain, 'Be removed and be cast into the sea,' it will be done. And whatever things you ask in prayer, believing, you will receive."