Owais al-Qarni whose epithet was “Abu Umar” was a Muslim mystic, martyr and philosopher of Yemen. He converted to Islam during the lifetime of the Holy Prophet (s), but never met him personally. He had asked his mother's permission to visit the Messenger of Allah, and she said: "You have my permission to go, see him once, and come straight back. If the Messenger is at home, you may meet with him; if not, come straight back here." Owais made a journey of three months on foot, from Yemen to Medina. Upon reaching Medina, he found that the Prophet (s) was not at home. So he returned back to his mother. He is highly respected for this and for being a loyal companion of the Commander of the Faithful, Imam Ali (a.s) whom he gave his allegiance and defended until he was martyred in the Battle of Siffin.
The incident concerning Owais Al-Qarni breaking teeth is not certain and does not seem to be authentic. There are but few historians who have narrated the incident.
Before dealing with the main question, it is good to have a glimpse of the life and personality of Owais Al-Qarni:
A) Owais Al-Qarni, also known as Abu Umar, was a great Muslim who lived during the life of Prophet Muhammad (s) and died fighting alongside Imam Ali (a) in the battle of Siffin. He is highly respected for this and for being a loyal companion of Imam Ali (a) during the last few years of his life. It is believed that that he accepted the religion of Islam during the life of the Prophet (s), despite never having the opportunity to meet him (s), due to the fact that he lived in Yemen, far away from Medina. In fact, he had asked his mother's permission to visit the Messenger of Allah, and she had said: "You have my permission to go, see him once, and come straight back. If the Messenger is at home, you may meet with him; if not, come straight back here." Owais Al-Qarani made a journey of three months on foot, from the Yemen to Medina. Upon reaching Medina, he found that the Prophet (s) was not at home. So he returned back to his mother. Although he was from Yemen, he settled in Kufa during Umar’s time.
It has been reported that when the Commander of the Faithful, Ali (a) saw him for the first time, he recognized him by his radiant face and said: “You must be Owais?” He said: “Yes, I am”. He said: “Are you from the tribe of Qaran?” He said: Yes, I am Owais Al-Qarni.”
B) As for Owais Al-Qarni’s spiritual rank and status, we shall suffice to quoting only a few traditions from the Holy Prophet (s):
1. Many times in the company of his followers, the Beloved Prophet (s) stated: "I can smell the breeze of Paradise from the land of Qaran, I love to see Owais Al-Qarani, Beware! Whoever meets him, give my greetings to him".
2. Someone asked: “Who is Owais Al-Qarni? The Messenger of Allah (s) replied: "He is an unknown person whom you do not seek to find when he is not amongst you and when he is amongst you, you do not notice him but you should know that more people shall enter Paradise through his intercession from my Community than there are people in the tribes of Rabi'a and Mudar. He will not see me but he has faith in me and finally he will die alongside my meritorious successor [Ali bin Abi Talib (a)] in Siffin.
3. The Commander of the Faithful, Ali (a) has been quoted as having said: “The Messenger of God (s) told me that I would meet a man from his nation (Ummah) who is called Owai al-Qarni. He is from the party of God (Hizbullah) and His Messenger. He will be martyred in the way of God and that more people shall enter Paradise through his intercession from his community than there are people in the tribes of Rabi'a and Mudar.”
C) Owais was a pious and noble man; he was one of the selected companions of the Commander of the Faithful, Ali (a); he was at a higher rank as compared to some other companions of the Imam. Fazl bin Shazan describes him as being higher in rank than many other pious people.
The Messenger of Allah said about Owais’ piety and nobility: “There are some people among my Ummah who because of not having a dress cannot go to a mosque and their Iman (faith) hinders them from asking people for any assistance. One of those people is Owais Al-Qarni.”
He used to stay awake at night and engage in prayers.
The question is regarding whether the story of Owais al-Qarni breaking his teeth out of love for the Prophet (s) is true or not. It has become famous on the tongues of the general public that Owais pulled out or broke all his teeth out of extreme sorrow when he heard that the tooth of the Messenger of Allah (s) had been harmed in the Battle of Uhud. This incident, though quoted by sources, does not seem to be authentic. We doubt the authenticity of the reports as well as its content.
 - Zahabi, Shams al-Deen Muhammad bin Ahmad, Tarikh al-Islam, researched by Tadammori, Umar Abdul Salam, vol.3, pg. 555, Darul Kitab al-Arabi, Beiruit, second edition, 1413; Ibn Athir al-Jazri, Ezzudin bin Al-Athir Abul Hasan Ali bin Muhammad, Asad Al-Ghabah, vol.1, pg. 179, Dar al-Fikr Publication, Beirut, 1409 A.H; Tarikh al-Tabari, Abu Ja’far Muhammad bin Jarir al-Tabari, researched by Muhammad Abulfazl Ibrahim, vol.11, pg. 662, Dar al-Turath Publication, Beirut, second edition, 1387 A.H.
 - See: Shaykh Mufid, The Battle of Jamal, translated by Mahdavi Damghalani, Mahmud, pg. 59, Nay Publications, Tehran, 2nd edition, 2004.
 - Ibn A’tham al-Kufi, Abu Muhammad Ahmad bin A’tham, Al-Fotuh, researched by Shiri, Ali, vol.2, pg. 544 and 545, Dar al-Adhwa Publications, Beirut, 1st edition, 1411 A.H; Tarikh al-Islam, vol.3, pg. 555, Sirat A’laam al-Nubala, vol.5, pg. 34, quoted by Nazim Zadeh Qummi, Sayyid Asghar, The Companions of Imam Ali (a), vol.1, Owai al-Qarni; Asad al-Ghabah, vol.1, pg. 179.
 - Tarikh al-Islam, vol.3, pg. 555; Asad al-Ghabah, vol.1, pg. 179.
 - Ibn Hajar al-Asqalani, Ahmad bin Ali, Al-Esabah, researched by Abdul Mawjud, Adil Ahmad and Mu’awadh, Ali Muhammad, vol.1, pg. 359, Darul Kutub al-Islmiyah Publications, Beirut, 1st edition, 1415 A.H; The Companions of Imam Ali (a), vol.1.
 - Asad al-Ghabah, vol.179; Tarikh al-Islam, vol.3, pg. 556; Al-Isabah, vol.1, pg. 359; Zarkuli, Khayr al-Deen, Al-A’lam, vol.2, pg. 32, Darul ‘Ilm Lil-Malayin Publications, Beirut, 8th edition, 1989; Sirat al-A’lam al-Nubala, vol.5, pg. 70 cited from “The Companions of Imam Ali (a)”, vol.1.
 - Kashshi, Abu Umar, Muhammad bin Umar bin Abdul Aziz, Rejal al-Kashshi, researched and edited by Dr. Mustafavi, Hasan, pg.98 hadith 156, Mashad University Press, 1490 A.H.
 - Ibn Shazan Qummi, Abul Shazan bin Jibrail, Al-Fadhael, pg.107, Razi Publication, Qom, 2nd edition, 1984; Majlisi, Muhammad Baqir, Behar al-Anwar, vol.42, pg. 155, Dar Ihya al-Turath al-Arabi Publications, Beirut, 2nd edition, 1403 A.H; Shaykh Hurr Amili, Muhammad bin Hasan, Ithbat al-Hodath bin-Nusus wal-Mu’jizat, vol.3, pg. 46, A’alami Publication, Beirut, 1st edition, 1425 A.H.
 - Al-Fadhael, pg. 107; Behar al-Anwar, vol.42, pg.155.
 - Mufid, Muhammad bin Muhammad, Al-Irshad fir Ma’refat Hojajillah Alal ‘Ibad, vol.1, pg. 316, Congress on the Life and Personality of Shaykh Mufid, Qom, 1st edition, 1413 A.H.; Tabarsi, Fadhl bin Hasan, I’lam al-Wara be A’alam al-Hoda (old edition), pg.170, Islamiyah Publications, Tehran, 3rd edition, 1390 A.H; Behar al-Anwar, vol.42, pg.147.
 - Rijal al-Kashshi, pg.98; The Companions of Imam Ali (a), vol.1.
 - Al-Awsiya, vol.1, pg.361; Hulyatul Awliya, vol.2, pg. 84 and Seyar A’lam al-Nubala, vol.5, pg. 76 cited from “The Companions of Imam Ali (a)”, vol.1.
- Hulyatul Awliya, vol.2, pg. 87 and SeyarA ’lam al-Nubala, vol.5, pg. 77.
 - A less famous account is that he was martyred in the Battle of Deylam and his grave is in A’ala tar Mount of Qazvin (Mustawfi Qazvini, Hamdullah bin Abi Bakr bin Ahmad, Tarikh Guzideh, researched by: Nawayee, Abdul Hussein, pg. 630, Amir Kabir Tehran, 3rd edition, 1985)
 - Al-Isabah,vol.1, pg. 359; Asad al-Ghabah, vol.1, pg. 180; Tarikh al-Islam, vol.3, pg. 556; Tarikh al-Tabari, vol.11, pg. 662, Tarikh Guzideh, pg. 631; Al-Manqari, Nasr bin Muzahim, Waq’at Siffin, researched by Harun, Abdul Salam Muhammad, pg. 324, Al-Moassesah al-Arabiyah al-Hadithah, Al-Qaherah, 2nd edition, 1382, Qom, Al-Mar’ah Al-Najafi Library, 1404 A.H.; Al-Tamimi Al-Sam’ani, Abu Sa’eid Abdul Karim bin Muhammad bin Mansoor, Al-Ansaab, researched by Al-Mu’allimi Al-Yamani, Abdul Rahman bin Yahya, vol.10, pg. 392, Majlis Daeratul Ma’aref al-Uthmaniyah, Haider Abad, 1st edition, 1382 A.H.; Sib bin Jawzi, The Lives and Virtues of the Family of the Prophet (s), translated by Ata’ei, Muhammad Reza, pg. 115, Astan Quds Razavi Publications, Mashad, 1st edition, 2000.
 - Tarikh Guzideh, pg. 630.