I say: On the contrary, he is known. Al-Bukhārī included his biography in al-Tārīkh, as did Ibn Abī Ḥātim, who reported that Ibn Maʿīn said: “ʿUthmān ibn Bishr al-Thaqafī is trustworthy.” The remaining narrators in the chain are trustworthy narrators of Muslim, apart from ʿAbd Allāh ibn al-Ḥakam; there is only slight weakness in al-Ṭāʾifī. He apparently is al-Balawī, whose biography is found in al-Tārīkh and in Ibn Ḥibbān’s al-Thiqāt (7/30), for he belonged to this generation. Thus, the chain is good.
This ʿAbd Allāh al-Ṭāʾifī has another chain that is more authentic than this one—the second route: Muʿtamir ibn Sulaymān narrated it, saying: I heard ʿAbd Allāh ibn ʿAbd al-Raḥmān al-Ṭāʾifī relate from his uncle, ʿAmr ibn Uways, from ʿUthmān ibn Abī al-ʿĀṣ, who said: “The Messenger of Allah (peace and blessings be upon him) appointed me, though I was the youngest of the six men from Thaqīf who had come to him. This was because I had recited Sūrat al-Baqarah. I said: ‘O Messenger of Allah, the Quran is slipping from my memory.’ He then placed his hand upon my chest and said: ‘O Satan, leave ʿUthmān’s chest!’ Thereafter, I did not forget anything that I wished to memorize.” Al-Bayhaqī recorded it in Dalāʾil al-Nubuwwah (5/308). Its chain is authentic.
The third route: Al-Ḥasan narrated it from him, saying: “I complained to the Prophet (peace and blessings be upon him) about my poor retention of the Quran. He said: ‘That is a Satan called Khanzab. Come close to me, O ʿUthmān!’ Then he placed his hand upon my chest, and I felt its coolness between my shoulders. Then he repeated the preceding words. Thereafter, I did not hear anything without retaining it.”