Imran bin Husayn sent for me during the illness in which he died and said, "I am going to tell you some hadiths from which Allah may benefit you after I am gone. If I live, keep them confidential, but if I die, then narrate them if you wish. Know that I have been greeted with peace, and know that the Prophet of Allah ﷺ combined Hajj and Umrah, after which no verse of Allah's Book was revealed forbidding it, nor did the Prophet of Allah ﷺ prohibit it. A man later said about it whatever he wished according to his own opinion."
و حدثنا محمد بن المثنى وابن بشار قال ابن المثنى حدثنا محمد بن جعفر عن شعبة عن قتادة
بعث إلي عمران بن حصين في مرضه الذي توفي فيه فقال إني كنت محدثك بأحاديث لعل الله أن ينفعك بها بعدي فإن عشت فاكتم عني وإن مت فحدث بها إن شئت إنه قد سلم علي واعلم أن نبي الله ﷺ قد جمع بين حج وعمرة ثم لم ينزل فيها كتاب الله ولم ينه عنها نبي الله ﷺ قال رجل فيها برأيه ما شاء
Muslim narrated from Ibn Muthanna and Ibn Bashar, from Ghundar, from Shuba, from Qatada, from Mutarrif, from Imran bin Husayn, that the Prophet, peace and blessings be upon him, combined hajj and umrah, and no scripture was revealed to prohibit that afterward. The hadith continues.He also narrated it from the same two, from Ghundar, from Shuba, from Humayd bin Hilal, from Mutarrif. The hadith of Shuba from Humayd bin Hilal is sahih, but the hadith attributed to Qatada was actually narrated by Ghundar from Saeed bin Abu Aruba, not from Shuba, and as far as I know, no one narrated it from Shuba except an unreliable narrator.