Grading: Its chain is "hasan".
Technical note / Defect ('illah): This is because of Abd al-Aziz bin Hatim (who is al-Marwazi al-Mu'addal).

Technical note / Defect ('illah): Muhammad bin Humayd al-Razi differed, in Ibn Asakir's "Tarikh Dimashq" (43/ 409): he narrated it from Harun bin al-Mughirah, from Amr bin Abi Qays, from Ammar al-Duhni, from Salim bin Abi al-Ja'd, from Masruq, from A'ishah (may Allah be pleased with her). Although Ammar al-Duhni is thiqah (trustworthy), Amr bin Abi Qays narrated from him, and he in turn narrated from Salim bin Abi al-Ja'd as well, the problem is that Muhammad bin Humayd al-Razi is "da'if al-hadith" (weak in hadith).

Reference / Source: This hadith is also narrated marfu' from Hudhayfah bin al-Yaman, in Ibn Sa'd (3/ 243), al-Bukhari's "al-Tarikh al-Kabir" (3/ 96), Ibn Shabbah's "Tarikh al-Madinah" (4/ 1249) and Ibn Adi's "al-Kamil" (5/ 205), by way of Bilal bin Yahya al-Absi, from Hudhayfah, from the Prophet (peace and blessings be upon him), who said: "Abu al-Yaqzan (Ammar) is upon the fitrah, Abu al-Yaqzan is upon the fitrah; he will never abandon it until he dies or old age makes him forget."
Grading: Its chain is "da'if" (weak) because of a break (inqita'), since Yahya bin Ma'in stated firmly that Bilal's narration from Hudhayfah is "mursal" (disconnected). Indeed, in the narration of Ibn Shabbah, and in one narration in al-Bukhari, Bilal's words are: "It reached me from Hudhayfah."