That is what he said! Khusayf is weak due to his poor retention. Al-Ḥāfiẓ said in al-Taqrīb: “Truthful, poor in retention, and became confused in his later years.” I say: His narration of this hadith is one of the things that confirms this, for he was inconsistent in narrating it: at one time he said, “from Muqsim,” and at another, “from ʿIkrimah,” as mentioned above.
Zuhayr said: Khusayf narrated to us from Saʿīd ibn Jubayr and ʿIkrimah concerning Allah Most High’s words, “It is not for a prophet to misappropriate [the spoils of war].” They both read it as “be defrauded.” He said: ʿIkrimah—or someone else—narrated from Ibn ʿAbbās, and then cited something similar. Al-Ṭabarī recorded it.
Ḥumayd al-Aʿraj also corroborated him from Saʿīd ibn Jubayr, who mentioned it in abbreviated form. Al-Ṭabarī likewise recorded it through Qazaʿah ibn Suwayd al-Bāhilī, from him. Both Ḥumayd and Qazaʿah are weak.
The hadith has another route from Ibn ʿAbbās which lends it strength. Al-Ṭabarānī recorded it in al-Muʿjam al-Kabīr (11174), al-Muʿjam al-Awsaṭ (5446—according to my numbering), and al-Muʿjam al-Ṣaghīr (no. 441—al-Rawḍ al-Naḍīr); and through him, al-Khaṭīb recorded it in Tārīkh Baghdād (1/372). He said: Muḥammad ibn Aḥmad ibn Yazīd al-Narsī al-Baghdādī informed us; Abū ʿUmar Ḥafṣ ibn ʿUmar al-Dūrī, the Quran reciter, informed us from Abū Muḥammad al-Yazīdī, from Abū ʿAmr ibn al-ʿAlāʾ, from Mujāhid, from Ibn ʿAbbās: He used to object to anyone who recited, “It is not for a prophet to misappropriate [the spoils of war],” and would say, “How can a prophet not be defrauded when he may be killed?! Allah Most High says: ‘They kill the prophets unjustly.’” Rather, the hypocrites accused the Prophet, peace and blessings be upon him, concerning some of the spoils, so Allah revealed: “It is not for a prophet to misappropriate [the spoils of war].”