Imam Ahmad bin Hanbal رحمہ اللہ said:
إِخراجُ النَّاسِ مِنَ السُّنَّةِ شَديدٌ
It is a very crucial and critical matter to exclude someone from the Ahlus Sunnah.
[as Sunnah lil Khallal 2/373, #513 sanad sahih]
Imam Darami رحمہ اللہ said:
والبِدعةُ أمرُها شَديدٌ، والمنسوب إليها سيء الحالِ بين أَظْهُرِ المسلمينَ، فلا تَعْجَلُوا بالبدعة حتَّى تستيقنوا وتعلموا أَحَقًّا قال أحدُ الفَرِيقَينِ أم بَاطِلاً؟ وكيف تستعجلون أن تَنْسِبُوا إلى البدعة أقوامًا في قَوْلٍ قَالُوهُ، ولا تَدْرُونَ أنهم أَصَابُوا الحقَّ في قولهم ذلك أم أَخْطَئُوهُ؟!
The matter of bidah (innovation) is a serious thing, and the person who has attributed to the bidah is considered a wicked man, thus, do not be hasty with the matters of bidah until and unless you make yourself sure that who said the truth and who's on the falsehood in between two, and how can you be so hasty and quick to declare someone an innovator according to their opinion, even though you are unaware that if they have reached to the truth or fell in the error.
[ar Radd ala Jahmiyah pg. 175]
