Here are 8 Bible verses about public prayer from the Old and New Testaments of the Holy Bible (King James Version), sorted from most to least relevant.
Matthew 6:5-6 KJV
And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward. But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
Matthew 14:23 KJV
And when he had sent the multitudes away, he went up into a mountain apart to pray: and when the evening was come, he was there alone.
Luke 18:10-14 KJV
Two men went up into the temple to pray; the one a Pharisee, and the other a publican. The Pharisee stood and prayed thus with himself, God, I thank thee, that I am not as other men are, extortioners, unjust, adulterers, or even as this publican. I fast twice in the week, I give tithes of all that I possess. And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner. I tell you, this man went down to his house justified rather than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted.
Luke 6:12 KJV
And it came to pass in those days, that he went out into a mountain to pray, and continued all night in prayer to God.
Mark 6:46 KJV
And when he had sent them away, he departed into a mountain to pray.
2 Peter 3:9 KJV
The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
1 Timothy 2:8 KJV
I will therefore that men pray every where, lifting up holy hands, without wrath and doubting.
Luke 3:21 KJV
Now when all the people were baptized, it came to pass, that Jesus also being baptized, and praying, the heaven was opened,