Musnad Ahmad 27:65

Muhammad ibn Fudayl narrated to us, from Bayan, from Wabarah, who said: A man said to Ibn Umar: "Shall I perform Tawaf of the House while I have entered into Ihram for Hajj?" He said: "And what is the harm in that?" The man said: "Indeed, Ibn Abbas forbade that." He said: "I have seen the Messenger of Allah (ﷺ) enter into Ihram for Hajj, and he performed Tawaf of the House, and [he performed Sa'i] between al-Safa and al-Marwah."