bhakta-svabhava,-ajna-dosa ksama kare
krsna-svabhava,-bhakta-ninda sahite na pare

Translation: A characteristic of a pure devotee is that he excuses any offense by an ignorant rascal. A characteristic of Krsna, however, is that He cannot tolerate blasphemy of His devotees.

Purport: The characteristic of a Vaisnava and the characteristic of the Lord mentioned in this verse are very significant. In His Siksastaka (3) Sri Caitanya Mahaprabhu has taught the characteristics of a Vaisnava:

trnad api su-nicena taror iva sahisnuna
amanina mana-dena kirtaniyah sada harih
[Cc. Adi 17.31]

A Vaisnava strictly follows this principle of being humbler than the grass and more tolerant than a tree, expecting no honor from others but offering honor to everyone. In this way, a Vaisnava is simply interested in chanting about the Supreme Personality of Godhead and glorifying Him. Haridasa Thakura epitomized this foremost order of Vaisnavism.

Krsna, however, cannot tolerate any insults or blasphemy against a Vaisnava. For example, Prahlada Maharaja was chastised by his father, Hiranyakasipu, in so many ways, but although Prahlada tolerated this, Krsna did not. The Lord therefore came in the form of Nrsimhadeva to kill Hiranyakasipu. Similarly, although Srila Haridasa Thakura tolerated the insult by Gopala Cakravarti, Krsna could not. The Lord immediately punished Gopala Cakravarti by making him suffer from leprosy. While instructing Srila Rupa Gosvami about the many restrictive rules and regulations for Vaisnavas, Sri Caitanya Mahaprabhu has very vividly described the effects of offenses at the lotus feet of a Vaisnava. Yadi vaisnava-aparadha uthe hati mata (Madhya 19.156). Offending or blaspheming a Vaisnava has been described as the greatest offense, and it has been compared to a mad elephant. When a mad elephant enters a garden, it ruins all the creepers, flowers and trees. Similarly, if a devotee properly executing his devotional service becomes an offender at the lotus feet of his spiritual master or another Vaisnava, his devotional service is spoiled.

Srila Prabhupada, Cc Antya 3.213