Musnad Ahmad 27:433

'Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from Salim, from Ibn 'Umar, that he used to dislike stipulating conditions in Hajj. He would say: "Is the Sunnah of your Prophet, may Allah bless him and grant him peace, not sufficient for you? For he did not stipulate conditions."