Imaam Abu Haneefah
He said: “It is not permissible for anyone to follow what we say if they do not know where we got it from.”
According to another report he said: “It is haraam for the one who does not know my evidence to issue a fatwa based on my words.”
and he said: “woe be to you Ya’qoob. Do not write down everything you hear from me, for surely I may hold an opinion today and leave it tomorrow, hold another tomorrow and leave it the day after”
And he said: “If I say something that goes against the Book of Allaah or the report of the Messenger (صلى الله عليه وسلم), then ignore what I say.”
And he said: “”Adhere to the athaar and the way of the salaf and beware of newly invented matters, for all of it is an innovation.”
He also said: “if a hadeeth is found to be authentic, that is my madhab”
Now, the opposers to the dawah salafiyyah, the dawah of ahl as-sunnah, claim that these statements were only for “Abu Haneefah’s students” which is an absurd saying! As what will the students do with such saying if not act according to them and teach this to their followers!?
Imaam Malik
He said: “I am only human, sometimes I make mistakes and sometimes I get things right. Look at my opinion and whatever is in accordance with the Qur’aan and Sunnah, take it, and whatever is not in accordance with the Qur’aan and Sunnah, ignore it.”
And he said: “There is no one after the Prophet (صلى الله عليه وسلم) whose words cannot be taken or left, apart from the Prophet (صلى الله عليه وسلم).”
Imaam al-Shafi’ee
He said: “There is no one who will not be unaware of some of the Sunnah of the Messenger of Allaah (صلى الله عليه وسلم). Whatever I say or whatever guidelines I establish, if there is a report from the Messenger of Allaah (صلى الله عليه وسلم) which is different to what I said, then what matters is what the Messenger of Allaah (صلى الله عليه وسلم) said, and that is my opinion.”
according to al-Haakim, Imaam Shafi’ee said: “There is no one among us who has not had a sunnah of Allaah’s messenger (صلى الله عليه وسلم) elude him or have one slip his mind; so no matter what rulings I have made or fundamental principles I have proposed, there will be in them things contrary to the rulings of Allaah’s messenger (صلى الله عليه وسلم). Therefore, the correct ruling is according to what Allaah’s messenger (صلى الله عليه وسلم) said, and that is my ruling.”
He also said: “The Muslims (of my time) were of a unanimous opinion that one who comes across an authentic sunnah of Allaah’s messenger (صلى الله عليه وسلم) is not allowed to disregard it in favour of someone else’s opinion.”
al-Haakim also collected from Imaam ash-Shafi’ee a similar statement to that of Imaam Abu Haneefah, that being “If a hadeeth is found to be saheeh, it is my madhab.”
He also said: “If I say something then compare it to the Book of Allaah and the sunnah of His messenger (صلى الله عليه وسلم) and if it agrees with them, then accept it and that which goes against them, then reject it and throw my saying against the wall!”
Imaam an-Nawawi in Tahdheeb al-Asma wa’l-Lughaat mentioned under the biography of Imaam Shafi’ee: “…then he travelled to al-‘Iraaq where he spread the knowledge of hadeeth and he established the madhab of its people – that is the madhab of the Ahl al-Hadeeth.”
Imaam Ahmad said: “Do not follow me blindly and do not follow Maalik or al-Shafi’ee or al-Awzaa’i or ath-Thawri blindly. Learn from where they learned.”
And he said: “The opinion of al-Awzaa’i and the opinion of Maalik and the opinion of Abu Haneefah are all mere conjecture and it is all the same to me. Rather evidence is to be found in the reports – i.e., in the shar’i evidence.”
Ibn Abdul-Barr stated in Jaami’Bayaan al-‘ilm that, “There are no scholars from this ummah to whom a hadeeth of the Prophet Muhammad (صلى الله عليه وسلم) was established and then they rejected it… If they had done so, their trustworthiness would have been in question, let alone them being taken as Imaams, since doing so (rejecting hadeeth) necessitates sinfulness.”
Shaykhul-Islaam Ibn Taymiyyah said: “No one has to blindly follow any particular man in all that he enjoins or forbids or recommends, apart from the Messenger of Allaah (صلى الله عليه وسلم). The Muslims should always refer their questions to the Muslim scholars, following this one sometimes and that one sometimes. If the follower decides to follow the view of an imam with regard to a particular matter which he thinks is better for his religious commitment or is more correct etc, that is permissible according to the majority of Muslim scholars, and neither Abu Haneefah, Maalik, al- Shafi’ee or Ahmad said that this was forbidden.”
Ibn al-Qayyim said: in his Qaeedah Nuniyyah:
“If you say “Allaah said, and His Messenger said”
the ignorant one will say “where is the saying of so and so?”
(adapted from the works of Shaykh Muhammad Salih al-Munajjid and also the book ‘Refutation of Zayd Shaakir’s ‘Introduction to Following a Madhab’‘)
AsbaulHadeeth.com 
Imaam Nawawi (rahmatullah alayh) says: This which Imaam Shaafi has said does not mean that everyone who sees a Saheeh Hadith should say: ‘This is the Math-hab of Shaafi, thus practising on the zaahir (text/external or apparent meaning) of the Hadith.This most certainly applies to only such a person who has the rank of Ijtihaad in the Math-hab. It is a condition that he overwhelmingly believes that Imaam Shaafi was unaware of this Hadith or he was unaware of its authenticity. And this is possible only after having made a research of all the books of Shaafi and similar other books of the Ashaab of Shaafi, those who take (knowledge) from him, and others similar to these (books). This is indeed a difficult condition (to fulfil). Few are there who measure up to this (standard).What we have explained has been made conditional because Imaam Shaafi had abandoned acting on the zaahir (text) of many Ahadith which he saw and knew. However by him was established proof for criticism in the Hadith or its abrogation or its specific circumstance or its interpretation, etc. (hence he was constrained to leave aside the hadith).”
(I’laaus Sunan, Vol. 2, page 225)
(when one comes across an authentic hadith- Should the person summarily abandon the teaching of the madhhab in favour of the hadith? Or should he dutifully stick to the madhhab and ignore the hadith? al-Majmu‘ (vol. 1 p. 136) Imam al-Nawawi provides us with the following guidelines:
“Any Shafi‘i who finds a hadith going against his madhhab should look into the matter [as follows]: If he possesses the complete requirements of ijtihad without restriction, or in that chapter, or [even] in that point [alone], he may independently practice upon [the hadith]. If he does not [possess it] and finds it difficult to go against the hadith, and his search for a valid explanation of the hadith [within his madhhab] does not provide a convincing solution, then he may practice upon the hadith with one condition, which is that another independent [mujtahid] imam other than al-Shafi‘i should have practiced upon it. This would then be a valid pretext for him to leave the madhhab of his imam.”
Brother It doesn’t say anywhere for the common people to start giving fataawa about saheeh hadeeth and what is the madhab of Imaam Shafi’ee, and I have yet to come across a person who calls themself salafi and claim that anybody is allowed to look up a hadeeth and give a ruling or that they can find a saheeh hadeeth which appears to contradict their madhab and say “this saheeh hadeeth must be the madhab of Imaam Shafi’ee and Abu Haneefah so I should throw their fatwa on the wall” this is strictly for the people of knowledge and I cant understand why that is so hard to understand for the blind followers who continue to attack the ahlul-Hadeeth with lies claiming that the salafis don’t follow one just to take the easiest rulings, and that they rule by their desires and that they claim to be more knowledgable that the four Imaams and they say the salafis think they are all qualified to pass rulings according to the Book and the Sunnah… who said this? did Shaykh al-Albaani say this? no! its a lie made up by the blind followers of madhabs