Musnad Ahmad 25:314

Hushaym narrated to us, Yazid ibn Abi Ziyad informed us, from Mujahid, from Ibn Abbas, that he said: "The Prophet, may Allah bless him and grant him peace, entered into the state of Ihram for Hajj. When he arrived, he performed Tawaf around the House, and between al-Safa and al-Marwah, and he did not shorten his hair, and he did not exit the state of Ihram because of the sacrificial animal (Hady). And he commanded those who had not brought the sacrificial animal to perform Tawaf, and to perform Sa'i, and to shorten their hair or shave it, then to exit the state of Ihram."