If jarh (narrator criticism) is issued due to partisanship, enmity, loathing, or the likes, then it is rejected, and only he who is rejected relies on it. In light of this, the statement of Imam Malik regarding Muhammad ibn Ishaq, the author of Al-Maghazi, that he is a dajjal from amongst the dajjals, was not accepted, since it is known that it stemmed from clear animosity. Rather, they (the imams of jarh wa ta’dil) affirmed that he was hasan al-hadith (an acceptable narrator), and the imams of hadith used him as a proof.
I have dealt with this issue more thoroughly in my treatise, Imam al-Kalam fi ma Yata’allaqu bi ‘l-Qira’ah Khalf ‘l-Imam. Likewise, Al-Nasa’i’s censure of Ahmad ibn Salih al-Misri, Al-Thawri’s censure of Abu Hanifah al-Kufi, Ibn Ma’in’s censure of Al-Shaf’i, Ahmad’s censure of Al-Harith al-Muhasibi, and Ibn Mandah’s censure of Abu Nu’aym al-Asbahani are not accepted, due to the same reason. There are many similar examples in the famous books of this discipline.
Hence, the scholars stated, “One’s criticism of a contemporary is not accepted.” That is, if it is without evidence, because being a contemporary often leads to personal animosity.