Anyone who loves true prayer, but gets angry and is resentful, is not blameless. For he is like one who wants to see well and clearly but shakes his eyes restlessly and nervously.
You will not be able to pray clearly if you are confused by material things and distracted by incessant cares. For prayer is a deposition (distancing the mind) of thoughts.
St. Nilos the Ascetic
Translated by Dr. Nick Stergiou