Al-Khallaal (rahimahullaah) said: It was said to Abu Abdillaah [i.e. Imaam Ahmad (rahimahullaah)]: Has a man sinned for rejoicing due to what afflicts the companions of Ibn Abee Du’aad? He said, ‘’Who would not rejoice with this?’’ [As-Sunnah 5/121]
Who was Ibn Abee Du’aad?
Ibn Abee Du’aad and Bishr al-Mireesee: These are the two that encouraged the ruler, Al-Ma’moon, to inflict punishment upon Imaam Ahmad (rahimahullaah) and upon others from the Scholars so as to extract from them the saying that the Qur’aan is created. [For further details see link: http://www.abukhadeejah.com/imaam-barbahaaree-on-whoever-a-praises-an-innovator-allaamah-fawzaan-explains/