Do not pass through the streets of the hot-tempered and quarrelsome, lest your heart be filled with anger, and the darkness of delusion dominate your soul.
~ St. Isaac the Syrian, The Ascetical Homilies, Homily 17
Source online:
http://www.orthodoxchurchquotes.com/category/sayings-from-saints-elders-and-fathers/st-isaac-the-syrian/page/2/