What is the teaching of Ahlu Sunnah?
There are different sects and groups in Islam. The splits have caused the real followers of the Prophet (ﷺ) and his companions the need to distinguish themselves. This was done by the name Ahlu Sunnah or Ahlu Sunnah wal Jama'ah.
Ahlu Sunnah and Ahlu Sunnah wal Jama'ah refer to the same group. These are the followers of the Prophet (ﷺ) and his Companions, who follow them according to the understanding of the pious predecessors.
The Prophet (ﷺ) said:
"Benu Israel split into 72 sects, and my Ummah will split into 73 sects. They are all in the fire except one."
Abdullah bin 'Amr then asked, "And who is that O Messenger of Allah?" He (ﷺ) said: "Whoever follows me and my companions." Sunan Tirmidhi 2641
Classified as Hasan by Tirmidhi.
The teachings of Ahlu Sunnah wal Jama'ah are written in the books of the pious predecessors. The teachings has been spread by the Companions, Tabi'in (students of the Companions) and Atba Tabi'in (followers of the Tabi'in).
Ahlu Sunnah take the middle ground in Islam. They evade extremism from both sides. This by living the true teachings and refraining from newly invented matters.
This group is a small part of the Ummah. It has been the majority of the Ummah before the innovations spread. Since there are different sects in Islam (73 sects), this makes the minority.
Awza'ee (a student of the Tabi'in) said: “Islam will not disappear, but it is Ahlu Sunnah that will disappear to the point that as many as one person will remain per country.” (Sharh Usool I'tiqaad #19 by Imam Lalikaee)
Sufyan ath-Thawri (a student of the Tabi'in) said: “Take good care of the followers of Ahlu Sunnah, for they are strangers. The numbers of Ahlu Sunnah wal Jama'ah are few." (Sharh Usool I'tiqaad 1/64 of Imam Lalikaee)
It is true that Islam does not focus on numbers. A person can also simply be on the truth if he is alone on it. The Jama'ah, which refers to the community (or body of Muslims) that follows truth, does not need to consist of large numbers.
Ibn Mas'oud radiyAllahu 'anhu said: "The Jama'ah is where the Haqq (truth) is, even if you are alone." (Sharh Usool I'tiqaad 1/122 no.160)
Nu'aym ibn Hammad said: "If the community gets corrupt, you must stick to the practice before it got corrupt. Even if you are alone, you would be the Jama'ah." (Sunan Tirmidhi 4/467)