Prayer

"Seeing then that we have a great High Priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession. For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin. Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need." Hebrews 4:14-16

"...we do not know what we should pray for as we ought, but the Spirit Himself makes intercession for us with groanings which cannot be uttered. Now He who searches the hearts knows what the mind of the Spirit is, because He makes intercession for the saints according to the will of God. " Romans 8:26-27

"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. " 1 John 5:14-15

“If you abide in Me, and My words abide in you, you will ask what you desire, and it shall be done for you. By this My Father is glorified, that you bear much fruit; so you will be My disciples." John 15:7-8 (This implies that we are so intimately joined to Him that His desire has become our desire and His will is our will.)

“And whatever you ask in My name, that I will do, that the Father may be glorified in the Son. If you ask anything in My name, I will do it." John 14:13-14 (Asking in His name implies actual oneness with Jesus and His Spirit, heart and will -- not just saying "in Your name.")

“...we also, since the day we heard it, do not cease to pray for you, and to ask that you may be filled with the knowledge of His will in all wisdom and spiritual understanding; that you may walk worthy of the Lord, fully pleasing Him, being fruitful in every good work and increasing in the knowledge of God; strengthened with all might, according to His glorious power, for all patience and longsuffering with joy; giving thanks to the Father who has qualified us to be partakers of the inheritance of the saints in the light. " Colossians 1:9-12

"...love your enemies, bless those who curse you, do good to those who hate you, and pray for those who spitefully use you and persecute you, that you may be sons of your Father in heaven." Matthew 5:44-45

“Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. For everyone who asks receives, and he who seeks finds, and to him who knocks it will be opened. Or what man is there among you who, if his son asks for bread, will give him a stone? Or if he asks for a fish, will he give him a serpent? If you then, being evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask Him!" Matthew 7:7-11

"I sought for a man among them who would make a wall, and stand in the gap before Me on behalf of the land..." Ezekiel 22:30

"Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much." James 5:16

The last verse shows part of the context and condition for the next promise. God doesn't offer us a carte blanche answer (He doesn't promise to give us whatever our flesh or self-centered human nature might want). His promises assumes we know and believe Him, live by His Spirit, follow His Word and long to do His will.

“Most assuredly, I say to you, he who believes in Me, the works that I do he will do also; and greater works than these he will do, because I go to My Father. And whatever you ask in My name, that I will do, that the Father may be glorified in the Son. If you ask anything in My name, I will do it.
      “If you love Me, keep My commandments. And I will pray the Father, and He will give you another Helper, that He may abide with you forever— the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him, for He dwells with you and will be in you. " John 14:12-1

"You did not choose Me, but I chose you and appointed you that you should go and bear fruit, and that your fruit should remain, that whatever you ask the Father in My name He may give you. These things I command you, that you love one another." John 15:16-17

But when people ignore His truth and reject His ways, He will not listen.

"If I regard iniquity [hold on to sin] in my heart, the Lord will not hear." Psalm 66:18

“Therefore do not pray for this people, nor lift up a cry or prayer for them, nor make intercession to Me; for I will not hear you." Jeremiah 7:16

"So do not pray for this people, or lift up a cry or prayer for them; for I will not hear them in the time that they cry out to Me because of their trouble." Jeremiah 11:14

"When you come to appear before Me,
Who has required this from your hand, to trample My courts?
Bring no more futile sacrifices; incense is an abomination to Me.
The New Moons, the Sabbaths, and the calling of assemblies—
I cannot endure iniquity and the sacred meeting.
Your New Moons and your appointed feasts My soul hates;
They are a trouble to Me, I am weary of bearing them.
When you spread out your hands, I will hide My eyes from you;
Even though you make many prayers, I will not hear...." Isaiah 1:11-15

"Then the Lord said to me, 'Do not pray for this people, for their good. When they fast, I will not hear their cry.... But I will consume them by the sword, by the famine, and by the pestilence.” Jeremiah 14:11-12

Jesus shows us what to pray

“...when you pray, do not use vain repetitions as the heathen do. For they think that they will be heard for their many words. Therefore do not be like them. For your Father knows the things you have need of before you ask Him. In this manner, therefore, pray:
      “Our Father in heaven, hallowed be Your name.
Your kingdom come. Your will be done on earth as it is in heaven.
Give us this day our daily bread. And forgive us our debts, as we forgive our debtors.
And do not lead us into temptation, but deliver us from the evil one.
For Yours is the kingdom and the power and the glory forever. Amen." Matthew 6:7-13

"I thank my God upon every remembrance of you, always in every prayer of mine making request for you … with joy, for your fellowship in the gospel from the first day until now, being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ….

     "For God is my witness, how greatly I long for you all with the affection of Jesus Christ. And this I pray,

that your love may abound still more and more in knowledge and all discernment,

that you may approve the things that are excellent,

that you may be sincere and without offense till the day of Christ being filled with the fruits of righteousness which are by Jesus Christ, to the glory and praise of God." Philippians 1:3-11