Prayer builds our relationship with God.

And it shall be that everyone who calls on the name of the Lord will be saved. (Acts 2:21)

If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him? (Luke 11:13)

The LORD is near to all who call upon Him, to all who call upon Him in truth. He will fulfill the desire of those who fear Him; He will also hear their cry and will save them. (Psalm 145:18-19)

I love those who love me; and those who diligently seek me will find me. (Proverbs 8:17)

Prayer helps us overcome temptation.

Keep watching and praying that you may not enter into temptation; the spirit is willing, but the flesh is weak. (Matthew 26:41)

No temptation has overtaken you but such as is common to man; and God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will provide the way of escape also, so that you will be able to endure it. (1 Corinthians 10:13)

For we do not have a high priest who cannot sympathize with our weaknesses, but One who has been tempted in all things as we are, yet without sin. Therefore let us draw near with confidence to the throne of grace, so that we may receive mercy and find grace to help in time of need. (Hebrews 4:15-16)

Prayer helps us determine God’s will.

But if any of you lacks wisdom, let him ask of God, who gives to all generously and without reproach, and it will be given to him. (James 1:5)

Call to Me and I will answer you, and I will tell you great and mighty things, which you do not know. (Jeremiah 33:3)

Prayer allows us to participate in God’s work.

If you abide in Me, and My words abide in you, ask whatever you wish, and it will be done for you. My Father is glorified by this, that you bear much fruit, and so prove to be My disciples. You did not choose Me but I chose you, and appointed you that you would go and bear fruit, and that your fruit would remain, so that whatever you ask of the Father in My name He may give to you. (John 15:7-8, 16)

Prayer is a weapon in spiritual warfare.

Put on the full armor of God, so that you will be able to stand firm against the schemes of the devil. For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places. Therefore, take up the full armor of God, so that you will be able to resist in the evil day, and having done everything, to stand firm.... With all prayer and petition pray at all times in the Spirit, and with this in view, be on the alert with all perseverance and petition for all the saints, (Ephesians 6:11-13, 18)

Prayer preceeds spiritual awakening.

If I shut up the heavens so that there is no rain, or if I command the locust to devour the land, or if I send pestilence among My people, and My people who are called by My name humble themselves and pray and seek My face and turn from their wicked ways, then I will hear from heaven, will forgive their sin and will heal their land. (2 Chronicles 7:13-14)

Prayer brings comfort.

The LORD sustains all who fall and raises up all who are bowed down. The LORD is righteous in all His ways and kind in all His deeds. The LORD is near to all who call upon Him, to all who call upon Him in truth. (Psalm 145:14, 17-18)

Then you will call upon Me and come and pray to Me, and I will listen to you. ‘You will seek Me and find Me when you search for Me with all your heart. (Jeremiah 29:12-13)

Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all comprehension, will guard your hearts and your minds in Christ Jesus. (Philippians 4:6-7)