Arrogance and having enmity for and envy of Muslims are all sins of the heart. These are bad attributes of which many people are unaware, because they do not know what they are or how to avoid them.
Arrogance: It is to reject the truth and to look down on people.
The Prophet, may God raise his rank, said:
الكبر بطر الحق وغمط الناس
Al-kibru batarul-haqqi wa ghamtun-nas.
Which means: “Arrogance is rejecting the truth and looking down on others.” (Related by Muslim.)
What is understood from this hadith is that arrogance is rejecting what one knows is right, because the person saying it is young, poor, a student, or weak. Looking down on people is like being arrogant with a poor person, because he is poor. Thus, the arrogant refuses to speak with him or talks to him in a haughty way.
Enmity: It is to hate a Muslim, to accept this feeling, and to act in accordance with this feeling.
The Prophet, sallallahu ^alayhi wa sallam, said:
من أحبَّ أن يزحزح عن النار ويدخل الجنّة فلتأته منيته وهو يؤمن بالله واليوم الآخر، وليأت إلى الناس بما يحب أن يؤتى إليه
Man arada ay yuzahzaha ^anin-Nari wa yudkhalal-Jannata, falta’tihi maniyyatuhu wa huwa yu’minu billahi wal yawmil-akhiri, wal ya’ti ilan-nasi bima yuhibbu ay yu’ta ilayh.
Which means: “He who wishes to be moved away from Hellfire, and be admitted into Paradise, let him die believing in Allah and the Day of Judgment, and let him treat people in the way which he would like to be treated.” (Related by Ibn Hibban and al-Bayhaqiyy.)
Envy: It is to hate and feel bitter about the endowment of Allah on a Muslim, whether it be worldly or religious, and to wish that it would be taken from that Muslim and would be bestowed upon oneself. This is a sin only if one does not hate this feeling and if one acts in accordance with it. If one hates the envy one feels, and does not act accordingly, then it is not a sin.