Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) reports from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) prayed while people behind him were reciting, and a man from among the Companions began forbidding them from reciting in the prayer. When they finished the prayer, a man turned to him and said: Were you forbidding me from reciting behind the Messenger of Allah (peace and blessings be upon him)? They argued until they put the matter before the Prophet (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) said: "Whoever is praying behind the imam, the recitation of the imam is his recitation." [Munkar (rejected). Abu Hatim said so in al-'Ilal 282]
A group narrated it thus from Abu Hanifah as connected (mawsul), while Abdullah bin al-Mubarak narrated it from him as mursal, without mentioning Jabir, and that is the preserved (mahfuz) version.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2896