Abu Hafs 'Umar ibn Shahin: Declared him trustworthy
Ibn Hajar al-'Asqalani: Trustworthy, he makes mistakes
Abd al-Wahid ibn Wasil al-Sadusi: Trustworthy, truthful, good, satisfactory
Muhammad ibn Ishaq ibn Khuzayma: I do not know of Khalaf being just or being discredited
Muhammad ibn Isma'il al-Bukhari: He is not followed in his hadith
Authors of Tahrir Taqrib al-Tahdhib: Trustworthy, strong in hadith, Abd al-Wahid ibn Wasil al-Haddad, who is trustworthy, declared him trustworthy, and we do not know of any discrediting remarks about him