What prayers should be said when performing prostrations?
They could be prayers of humbling oneself before God and confessing one’s sins before Him, along with asking for mercy. For each prostration, the individual can confess a sin and accuse himself before God with the words: ‘Have mercy on me, 0 God, for I have done such and such’.
They could be prayers of thanksgiving in which the person brings to mind God’s mercies to him or to his loved ones, and in each prostration he can recall some of God’s good gifts.
They could be prayers of petition, in which the one praying mentions something that he would like to have personally, or he wishes that God grants to the Church or to someone else. In fact prostrations can be accompanied by any such suitable kind of prayer.