Narrated Abu Huraira: The Prophet said, "Do not deny your fathers (i.e. claim to be the sons of persons other than your fathers), and whoever denies his father, is charged with disbelief."
Hadith Referenceصحيح البخاري / كتاب الفرائض / 6768
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة
Hadith Commentary: In the era of ignorance (Jahiliyyah), when people would adopt someone as a son, that son would attribute himself to the adoptive father instead of his biological father. Allah, the Exalted, has taken strict notice of this matter in Surah Al-Ahzab (: Al-Ahzab 33:5). Despite the prohibitive command, even today most people attribute an adopted child to themselves. However, this is absolutely not permitted in the Shari‘ah. Ibn Battal has written that if such fame (attribution) occurs unintentionally, it does not fall under the aforementioned warning. (: Fath al-Bari 12/67) In any case, the disbelief (kufr) mentioned here does not refer to real disbelief that expels a person from the fold of Islam; rather, what is meant is ingratitude for blessings. And Allah knows best.
Source: Hidayat al-Qari: Commentary on Sahih Bukhari, Urdu, Page: 6768
Muhammad bin Rāfi’ and Hajjāj bin ash-Shā’ir narrated to me, they said Abd ur-Razzāq narrated to us, he said Ma’mar said: ‘I did not see Ayyūb speaking ill of anyone, ever, except for Abd al-Karīm- meaning Abū Umayyah’. So he mentioned him and said, may Allah have mercy on him ‘He is not trustworthy- he had asked me about a Ḥadīth of Ikrimah then said ‘I heard from Ikrimah’ [when relating the Ḥadīth].’
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary:Benefits and Issues: It is not sufficient for someone to be considered unreliable (non-thiqah) merely on this basis, because it is possible that he heard that hadith from ‘Ikrimah (rahimahullah), then forgot it, and asked in order to remember it. However, since his weakness was established by other indications and circumstances, the hadith scholars (muhaddithin, rahimahumullah) declared him weak. Therefore, Sufyan ibn ‘Uyaynah (rahimahullah), ‘Abdur-Rahman ibn Mahdi (rahimahullah), Ahmad ibn Hanbal (rahimahullah), Yahya ibn Sa‘id al-Qattan (rahimahullah), and other eminent imams have declared him weak.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 62