All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Abul-Khattaab ibn Dihyah who Abu Shaamah quoted in Al-Baa‘ith and Ibn Hajar in Az-Zahr An-Nadhir is the same person who Ibn Hajar criticized in his biography of him in the Lisaan Al-Meezaan. His name was ‘Umar ibn Hasan ibn ‘Ali ibn Muhammad, also known as Al-Jumayyal, ibn Faraj ibn Khalaf Al-Andalusi Ad-Daani.
In his biography in the Meezaan and the Lisaan and in other books he was described as being a learned man, well-versed and having insightful knowledge about the Hadeeth, its language, men and meanings.
However, the scholars criticized him regarding some matters, like his claiming to be from the lineage of the Companion Dihyah Al-Kalbi, and also his claiming to hear and preserve what he had not heard or preserved, and his indulging very much in criticizing the Imaams, and he was also criticized for behavioral matters, such as being proud of himself, being unjust to people when he assumed the office of judge, among other things.
Nonetheless, all this does not prevent from acquiring what is right and correct from him. It is not a condition that one is infallible or completely righteous in order to acquire knowledge from him. Rather, truth is accepted and transmitted from whoever presents it, and the scholars have been often observed as doing so – they do not abstain from quoting and acquiring knowledge from people who have been criticized for something as long as what is quoted from such a person is right and true.
Allaah Knows best.