The Levels of the Companions
A believer who saw the Prophet even for a very short time is called a Companion but among the people who saw him, there are those who became Muslims before the others, those who lived near him throughout their lives and those who made jihad with him. There are also those who tried very hard with him to spread Islam and to make Allah's name known. There are also those who were insulted and threatened together with the Prophet, who were tortured, who had to migrate to other towns by leaving their properties, countries and families and who were martyred in the way of Allah. It is quite natural that there are differences of levels and ranks among them. It is not possible to regard all Companions to be at the same level in terms of virtue. Due to these differences, Islamic scholars divided them into levels/ranks/classes.
Accordingly, the most virtuous person in the world after the Prophet is Hz. Abu Bakr, Hz. Umar, Hz. Uthman and Hz. Ali respectively. After the Four Caliphs, the most virtuous ones are the people who were given the glad tidings of going to Paradise while they were alive called Ashara al-Mubashshara (the ten who were promised Paradise); they are listed after the four caliphs in our book.
The classification of the Companions based on their virtues is as follows:
• Those who accepted Islam at the beginning like the Four Caliphs.
• The People of Dar an-Nadwa. After Hz. Umar became a Muslim, he was taken to the Prophet, who was at Dar an-Nadwa. The Makkans who became Muslims during this period when Islam was declared openly are regarded among this group.
• The Companions who migrated to Abyssinia.
• The People of the First Aqaba. The Muslims of Madinah who paid allegiance to the Prophet in Aqaba.
• The People of the Second Aqaba.
• The first muhajirs who joined the Prophet in Quba before he arrived in Madinah.
• Those who took part in the Battle of Badr. The Prophet (pbuh) stated the following about them:
"Allah is definitely pleased with the People of Badr. Do whatever you wish. Allah has forgiven you."
• Those who migrated between the Battle of Badr and the Treaty of Hudaybiya.
• Those who took part in the Allegiance of Ridwan.
The Allegiance of Ridwan took place when the Prophet and the Companions were prevented from performing umrah by Makkan polytheists. The Prophet signed a treaty with the polytheists to perform umrah for the next year. Hudaybiya was the name of the place where there was a well. The following is stated about these people in the chapter of al-Fath:
"Allah's Good Pleasure was on the Believers when they swore Fealty to thee under the Tree."
• The Companions who migrated between the Treaty of Hudaybiya and the Conquest of Makkah. People like Khalid bin Walid, Amr bin As and Abu Hurayra are among these Companions.
• Those who became Muslims after the Conquest of Makkah.
• The children who saw the Prophet during the Conquest of Makkah and the Farewell Hajj. 
 Tajrid as-Sarih Translation, 1: 28.