Ijmaa’a, ie. consensus, comes from jamaa’a, which means to gather or to collect.
One of the main evidences the followers of Ijmaa’a as-Sahaabah misrepresent is:
وَمَن يُشَاقِقِ الرَّسُولَ مِن بَعْدِ مَا تَبَيَّنَ لَهُ الْهُدَىٰ وَيَتَّبِعْ غَيْرَ سَبِيلِ الْمُؤْمِنِينَ نُوَلِّهِ مَا تَوَلَّىٰ وَنُصْلِهِ جَهَنَّمَ ۖ وَسَاءَتْ مَصِيرًا
And whoever opposes the Messenger after what has been clarified of the guidance and follows other than the path of the believers – We will turn him to what he has turned to and We will burn him in Hell. [An-Nisa 4:115]
So who are the believers and what is their path?
Allaah describes the attributes of the believers in Surah al-Mu’minoon and many other ayaat throughout the Qur’aan, such as: they hear and obey, they refer judgment back to Allaah and his Messenger, they maintain their prayers, etc.
The believers’ path is nothing but Islaam, conviction and submission to all that Allaah has revealed, and whoever opposes the Messenger after what has been clarified of the guidance, are kaafirs who obviously don’t follow the path of the believers.
Some argue that the path of the believers is whatever they have all agreed upon. This can be taken 3 ways:
– They all agree to that which Allaah has sent down and nothing beyond that.
– They all agree to a particular understanding that is derived from that which Allaah has sent down.
– They all agree to something in which no revelation has been sent down.
However, these same people dispute over what is intended by the word believers in the ayah. Is it only the Prophet’s companions or all the believers from the time since Allaah sent down the Dhikr up until Qiyama?
The verse clearly does not say Sahaabah. It says believers and the believers cannot be restricted to the Prophet’s companions alone. Because we know there were other believers who lived during that time and they never met the Prophet, such as Najashi and Owais al-Qarni.
It is impossible to ascertain the names of all the Prophet’s companions to even know how exactly each one understood a particular verse or narration from the Prophet. Actually we do not even know how many Sahaabah existed. Therefore, it is impossible to know whether or not there was any consensus among them.
There is no guarantee that the Prophet’s companions will collectively come to the right conclusions during his lifetime or afterwards. This is an assumption for which there is no proof, in fact the companions all disobeyed the Prophet when he told them to shave their heads and sacrifice their animals when the mushriks prevented from making Hajj. How can we assume they will never err after the Prophet’s death when the Prophet’s not there to clarify and correct them?
Those who were with the Prophet are not necessarily those who have the best understanding of what has been revealed, and those who never met the Prophet may understand it better. This possibility was told to us by Allaah’s Messenger himself:
…اللَّهُمَّ اشْهَدْ، فَلْيُبَلِّغِ الشَّاهِدُ الْغَائِبَ، فَإِنَّهُ رُبَّ مُبَلِّغٍ يُبَلِّغُهُ مَنْ هُوَ أَوْعَى لَهُ فَكَانَ كَذَلِكَ…
…O Allaah be witness! Let those who are present convey to those who are absent. For perhaps the one to whom it is conveyed will understand it better than the one who conveys it….
 The full incident can be found in Saheeh al-Bukhaari, Book of Conditions, Book 54, Narration no. 19
 This narration is reported in several major books of hadeeth like Musnad Ahmed, Saheeh al-Bukhaari, Sunan ibn Maajah.