Abdul A’alaa narrated from Imam Sadeq (AS) who narrated from the Prophet of Islam (PBUH) who said:

The biggest arrogance is to be ungrateful of creation and ignorant of the truth. I asked Imam Sdaeq (AS) what is the meaning of this? Imam (AS) replied: To be ignorant of the truth and to ignore it, avoiding the truth, and making sarcastic comments to followers of the truth and reproach as well as criticize them [1].

[1] Akhlaq-e-Rabbani, Ayatollah Mojtaba Tehrani (RA), Page 42.