I was sitting with Ali when he said, "I entered upon the Messenger of Allah ﷺ when no one was with him except Ayesha
, and he said, 'Son of Abu Talib, how will you deal with such and such a people?'I replied, 'Allah and His Messenger know best.'He said, 'A people will come out of the East who recite the Quran, but it will not pass beyond their throats. They will pass out of the religion as an arrow passes through its target. Among them will be a man with a deformed hand, as though his hand were the breast of an Ethiopian woman.'"
حدثنا عبد الله حدثني أبو خيثمة زهير بن حرب حدثنا القاسم بن مالك المزني
كنت جالسا عند علي رضي الله عنه فقال إني دخلت على رسول الله ﷺ وليس عنده أحد إلا عائشة رضي الله عنها فقال يا ابن أبي طالب كيف أنت وقوم كذا وكذا قال قلت الله ورسوله أعلم قال قوم يخرجون من المشرق يقرءون القرآن لا يجاوز تراقيهم يمرقون من الدين مروق السهم من الرمية فمنهم رجل مخدج اليد كأن يديه ثدي حبشية
Its isnad is sahih. Qasim bin Malik Muzani is trustworthy. Kulayb bin Shihab Jarmi, the father of Asim, Bukhari said in al-Kabir 4/1/229 that he heard from Ali and Umar. See 1330, 1345, and also see 656. See also the following hadith, where there is further discussion.