It is narrated from Ibn Buhaina (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) stood up after two rak‘ahs in the Zuhr prayer and did not sit (i.e., did not recite the tashahhud). When he completed the prayer, he performed two prostrations first and then said the salam.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 328
Hadith Takhrijأخرجه البخاري: السهو، باب ما جاء في السهو إذا قام من ركعتي الفريضة: 1225.