It is narrated that a man came to the Prophet of Islam (PBUH), stood in front of him and asked:

O’ the Prophet of Allah (SWT), what is the religion? The Prophet (PBUH) replied: Good temper. That man went to the right side of the Prophet and asked again: O’ the Prophet of Allah (SWT), what is the religion? The Prophet (PBUH) replied: Good temper. Then that man went to the left side of the Prophet (PBUH) and repeated the same question, and heard the same reply. And then went behind the Prophet (PBUH) and asked the same question. The Prophet (PBUH) looked at him and said: Do you not pay attention that the religion is that, you do not get angry, and do not behave harshly towards the creatures of Allah (SWT) [1].

[1] Beharul Anwaar, Vol. 6, Page 393.

Source:en.shafaqna.com