Hadith 8:571
Abu Bakr narrated to us, he said: Hafs narrated to us, from Hajjaj, from Ata and Abd al-Rahman ibn al-Aswad, that they both said: "Perform the tahallul (exit from ihram), then perform the ish'ar (marking of the sacrificial animal)."
حدثنا أبو بكر قال حدثنا حفص عن حجاج عن عطاء وعبد الرحمن بن الأسود أنهما قالا تحلل ثم تشعر