Quoting: Insults Come From Ignorance

Rabbi Yitzhak Meltzin never got angry with another person. If someone insulted him, he always ignored it. He said, “It is wrong to insult someone, and if this person insulted me it is because he lacks the necessary understanding. So why should I be angry at someone for his ignorance?”

Sources: Tnuas Hamussar; Rabbi Pliskin’s Gateway to Happiness