"Undisturbed calmness of mind is attained by cultivating friendliness toward the happy, compassion for the unhappy, delight in the virtuous, and indifference toward the wicked."
- The Yoga Sutra by Patanjali, Book 1, Aphorism 33
If you are interested in learning more about the Yoga Sutra with down-to-earth advice and commentary, I highly recommend the translation by Sri Swami Satchidananda. Cheers!