On Prayer by Tertullian
Chapter XII.--We Must Be Free Likewise from All Mental Perturbation.
Nor merely from anger, but altogether from all perturbation of mind, ought the exercise of prayer to be free, uttered from a spirit such as the Spirit unto whom it is sent. For a defiled spirit cannot be acknowledged by a holy Spirit, nor a sad by a joyful, nor a fettered by a free. No one grants reception to his adversary: no one grants admittance except to his compeer.