The Imaam, al-Haafidh al-Dhahabi said, “And if—every time an Imaam made a mistake in his ijtihaad in some issues which he can be forgiven in—we rose up against him and declared him to be an innovator, and boycotted him, then Ibn Nasr would not be safe with us, nor Ibn Mandah, and nor people greater than both of them.

And Allaah is the One who guides the creation to the Truth, and He is the Most Merciful of those who show mercy, and we seek refuge with Allaah from desires and coarseness.”

And he said, “Thereafter, verily, when the issues that a great scholar from the people of knowledge is correct in are numerous, and his striving to come to the truth is known, and his knowledge is vast, and his intelligence has become apparent, and his righteousness and his following [the Quran and the Sunnah] is known, he is forgiven for making a mistake—and we do not declare him to be misguided, nor do we throw him aside and forget his good deeds … yes, and we do not follow him in his innovation or mistake and we hope that he will repent from that.”

Siyar A’laam an-Nubalaa, 14/40 and 5/271.

Taken from http://giftsofknowledge.net/category/methodology/