23 And being let go, they went to their own companions and reported all that the chief priests and elders had said to them. 24 So when they heard that, they raised their voice to God with one accord and said: "Lord, You are God, who made heaven and earth and the sea, and all that is in them, 25 who by the mouth of Your servant David F19 have said: 'Why did the nations rage, And the people plot vain things? 26 The kings of the earth took their stand, And the rulers were gathered together Against the Lord and against His Christ.' F20 27 "For truly against Your holy Servant Jesus, whom You anointed, both Herod and Pontius Pilate, with the Gentiles and the people of Israel, were gathered together 28 to do whatever Your hand and Your purpose determined before to be done. 29 Now, Lord, look on their threats, and grant to Your servants that with all boldness they may speak Your word, 30 by stretching out Your hand to heal, and that signs and wonders may be done through the name of Your holy Servant Jesus." 31 And when they had prayed, the place where they were assembled together was shaken; and they were all filled with the Holy Spirit, and they spoke the word of God with boldness.
There are many more examples of public prayer in the New Testament.
The rule: There is a place of personal prayer and there is a place for public prayer.
From Mathew:
6:7 But when ye pray, use not vain repetitions, as the heathen [do]: for they think that they shall be heard for their much speaking.
6:8 Be not ye therefore like unto them: for your Father knoweth what things ye have need of, before ye ask him.
6:9 After this manner therefore pray ye: Our Father which art in heaven, Hallowed be thy name.
I've never understood why its ok to ignore this.