Source for the below: Posted by Umm Mujahida As Salafiyyahon west-london_dawah group
(I made notes on the main points but it's not word for word).
When you're warning against a person it's because he is opposing the manhaj (of the salaf) and so you advise him until he repents. This person is at a stage where he has to be avoided and he needs to be advised with the truth. Know the truth and you will know its people. He is in a stage where the scholars have yet to declare him an innovator, he is being advised so he will either accept the truth or deny it.
You may be deceived by him so you have to stay away from him until the ulama say more about him. As for someone speaking ill of the people of the Sunnah, then he is actually speaking ill of the Sunnah so he is a misguided innovator. We love and hate for Allah and this is a principle in boycotting and this is walaa wal baraa. Some people say salafis are harsh, but harshness is if they criticized without valid reasons. Shaykh Rabee advises before he refutes the innovators, the shaykh is just.
If you refute someone without proofs, that's dhulm (oppression). But when Shaykh Rabee Hadee al-Madkhalee refutes innovators, he has proof by quoting from the innovators' own books and tapes, which reveal their innovations. Shaykh Rabee is past 80 years old and has refuted about 20 people in his lifetime so far.
Compared to the Salaf (early Muslim scholars), this isn't much because they refuted 100s or 1,000s of people yet some still accuse Shaykh Rabee of being harsh. When Shaykh Rabee refuted the innovators, you wont find any other salafi scholars saying he was wrong, so they agreed with him too. And if there were some scholars who didn't agree with him, you will find that after some time they returned to Shaykh Rabee's opinion.
Scholars are of different levels: some more involved in fiqh, some more in refuting bid'ah, some more in arabic grammer. You can't reject the scholar who refutes with proof just because other mashayikh are quiet on the issue. These mashayikh did not turn to address this fitan. And just because they're quiet, doesnt mean they agree with the fitan/trial of an innovator.
If a certain shaykh hasn't spoken about an innovator, maybe he doesnt know his condition as well as the other shaykh who did. The latter looked into the issue in more depth. Even if there was a difference amongst scholars over an innovator, you follow the proof and return to the truth. You are sinning if you follow falsehood, using as an excuse that you follow that shaykh instead.
For example, if a doctor came who specialises in heart surgery spoke about a cure and another general doctor came and spoke, the common folk would give precedence to the speech of the doctor who was a specialist in that field. So likewise, when you want to know about the innovators, you would go the shaykh who has more knowledge of the field than the rest of the scholars because he specialised in this.
Someone asked about the Jordian mashayikh so I said to them - you should fear Allah. The Jordians aren't scholars but are students of ilm because they are less in their age and ilm. So to say they are mashayikh is dhulm.
What we mean when we say 2 scholars are contemporaries is that when they are close in age and in knowledge.
If someone falls into a mistake by purpose and it's clarified to him yet he persists then you can critisize that person. This is different to the case of a person who makes a mistake inadvertently.
If some scholars have refuted innovators, this suffices the other scholars from doing so because it's fard ul kifayah. Even if only 1 scholar refutes with proofs and the rest remain quiet, then this is sufficient. You don't require a group of scholars to refute, this is the khalafi manhaj.
If a scholar criticizes someone, you can quote his statements to the people. And if they don't accept the statement of the scholars, then they wont accept it from you! The beginner student of ilm should not declare people innovators, this is for the scholars or those students of ilm who are qualified. Don't precede the scholars in these affairs. Do not enter into debating.