A pure devotee immediately becomes fiery with anger when he sees that Lord Visnu or His devotee is insulted
SB Canto 4
The saintly sages continued: This impious, impudent man does not deserve to sit on the throne at all. He is so shameless that he even dared insult the Supreme Personality of Godhead, Lord Viṣṇu.
One should not at any time tolerate blasphemy and insults against Lord Viṣṇu or His devotees. A devotee is generally very humble and meek, and he is reluctant to pick a quarrel with anyone. Nor does he envy anyone. However, a pure devotee immediately becomes fiery with anger when he sees that Lord Viṣṇu or His devotee is insulted. This is the duty of a devotee. Although a devotee maintains an attitude of meekness and gentleness, it is a great fault on his part if he remains silent when the Lord or His devotee is blasphemed.