From Khilas, from Ibn Utbah, transmitted as mursal.
عن خلاس عن ابن عتبة مرسل
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Its isnad is sahih, though it is mursal like the one before it. This isnad is not to be taken at face value, otherwise it would be disconnected in a way that cannot be repaired. Rather, Imam Ahmad means that Abdul-Wahhab bin Ata Khafaf followed Abdullah bin Bakr, narrating the hadith from Saeed bin Abu Aruba, from Qatada, from Khilas, from Ibn Utba, as a mursal report, with no mention of Ibn Masud in it.