In his Sahih ...
In his Sahih , al-Bukhari says, “Whoever kept company with the Messenger of Allah or saw him is one of his sahaba .” Ahmad ibn Hanbal says, “The best of people, barring those who accompanied the Messenger of Allah during the Battle of Badr, is whoever kept him company for a year, a month, or a day, or who even saw him.
He is respected proportionately according to the length of time he accompanied the Prophet.”[^7] In his book Al-Isaba fi Tamyiz al-Sahaba , Ibn Hajar says, “Anyone who quotes one single hadith of the Prophet or even one word, or who has seen him and is a believer in him, is a sahabi .
So is anyone who has met the Prophet believing in him then dies as a Muslim, whether he kept him company for a long or a short period of time, whether he quotes him or not, whether he has participated in a campaign with him or not, whether he saw him but did not meet him, or whether he could not see him due to certain obstacles.”[^8] The vast majority of “Ahlul Sunnah wal Jama`ah” share this view.
They label as sahabi anyone who saw the Prophet or was born during his life-time even if he had not reached the age of distinguishing right from wrong. There is no better proof than their counting Muhammad ibn Abu Bakr as one of the sahaba although when the Messenger of Allah died, Muhammad ibn Abu Bakr was only three months old...! This is why we find Ibn Sa`d classifying the sahaba into five categories or, as he calls them, classes ( tabaqat ) in his renown book Tabaqat ibn Sa`d .
The Naisapuri governor who wrote Al-Mustadrak , however, categorizes them into twelve classes as follows: First Class includes those who accepted Islam prior to the Hijra, such as the righteous caliphs. Second Class includes those who attended Dar al-Nadwa . Third Class includes those who migrated to Abyssinia (Ethiopia). Fourth Class includes those who attended the First Aqaba [allegiance swearing]. Fifth Class includes those who attended the Second Aqaba.
Sixth Class includes those who migrated to Medina following the Prophet's migration thereto. Seventh Class includes those who participated in the Battle of Badr. Eighth Class includes those who migrated after Badr and prior to the [treaty signing at] al-Hudaybiya. Ninth Class includes those who participated in Bay`at al-Ridwan. Tenth Class includes those who migrated after the Hudaybiya and prior to the conquest of Mecca such as Khalid ibn al-Waleed, Amr ibn al-As, and others.