Imam Malik's Muwatta, Chapter: Speech

Malik related to me that he heard that Isa ibn Maryam used to say, "Do not speak much without the mention of Allah for you will harden your hearts. A hard heart is far from Allah, but you do not know. Do not look at the wrong actions of people as if you were lords. Look at your wrong actions as if you were slaves. Some people are afflicted by wrong action and some people are protected from it. Be merciful to the people of affliction and praise Allah for His protection."