Hadith 8:2350
Abu Bakr narrated to us, he said: Humayd narrated to us, from Hasan, from Layth, from Mujahid, and from ‘Ata’, and from Tawus, or one of them, regarding a man who entered into the state of Ihram for Hajj. They both said: If he wishes, he may include an ‘Umrah with it, and thus he would be a Qarin (performing Hajj Qiran), and he shall offer a sacrificial animal (Hady).
حدثنا أبو بكر قال حدثنا حميد عن حسن عن ليث عن مجاهد وعن عطاء وطاوس أو أحدهما في رجل أهل بالحج قالا إن شاء جعل معها عمرة فكان قارنا واهدى هديا