Acts 2:42

In prayers] lit. 'in the prayers,' i.e. the public prayers of the Church. These would probably be partly liturgical, after the example of the Temple and the Synagogue (cp. the liturgical addition to the Lord's Prayer, Matthew 6:13; AV), and partly extempore. Extempore prayer was allowed to be offered at the celebration of the Lord's Supper by the Christian prophets (see the 'Didache'), and was apparently still in use in the age of Justin Martyr (150 a.d.), but shortly after this the public prayers of the Church became exclusively liturgical.