Matthew 21:22 - Prayer Power.

Mat.21:22: Prayer Power.

Mat 21:22 (KJV)  And all things, whatsoever ye shall ask in 
prayer, believing, ye shall receive. 

Mat 21:22 (REB)  Whatever you pray for in faith you will receive.

Mat 21:22 (EAV)  And whatever you ask for in prayer, having 
faith and [really] believing, you will receive. 

This verse was not a guarantee that the disciples could get 
anything they wanted simply by asking Jesus and believing. God does not 
grant requests that will hurt people or that will violate his own 
nature or will. Jesus' statement was not a blank check to be filled in 
by believers, not a "name it and claim it" theology. To be 
fulfilled, requests made to God in prayer must be in harmony with the 
principles of God's kingdom. They must be made in Jesus' name (John 
14:13-14). The stronger our faith, the more likely our prayers will be in 
union with Christ and in line with God's will; then God will be happy 
to grant them. God can do anything, even what seems humanly 
impossible. (Life Application Commentary) 

Jesus makes it plain that our asking must be according to God's 
will; we must ask for the things that He has promised, and whatever we 
receive must be used in doing His will. The conditions met, the promise 
is unequivocal.  For the pardon of sin, for the Holy Spirit, for a 
Christlike temper, for wisdom and strength to do His work, for any gift He 
has promised, we may ask; then we are to believe that we receive, 
and return thanks to God that we have received.  We need look for no 
outward evidence of the blessing. The gift is in the promise, and we may 
go about our work assured that what God has promised He is able to 
perform, and that the gift, which we already possess, will be realized 
when we need it most. ED257-258 

Where we get wrong in prayer is that we are so self-willed.  We 
set ourselves to pray for things; we vow to sit up all night to 
bring God round to our way of thinking; we use strong cryings, tears, 
and protestations...  And then we are surprised if the fig-tree does 
not wither, or the mountain remove.  Where are we wrong?...  There 
is too much of self and the energy of the flesh in all this.  We 
can only believe for a thing when we are in such union with God that 
his thought and purpose can freely flow into us, suggesting what we 
should pray for, and leading us to that point in which there is a 
perfect sympathy and understanding between us and the divine mind....  
Then the Spirit will lead you to ask what is in the will of God to 
give, and you will know instantly that the Spirit intercedes within 
you according to the will of God.  [F. B. Meyer; Our Daily Homily; 
Spirit Filled Life Daily Devotional Bible] 

"Faith" and "believing" in the NT are expressions that indicate 
a sincere trust in God, and a genuine relationship with Him. 
Christ's relationship with the Father made the miracle of answered prayer 
not only a possibility, but a certainty. And when our prayers grow 
out of a genuine relationship with the Lord, our prayers too can be 
expressions not of uncertain hope, but of real confidence that we "will 
receive." [Victor Bible Background Commentary] 

Faith works miracles and is the basis for answered prayer. 
[Nelson SB]