Yahya related to me from Malik from Ayyub ibn Abi Tamima as-Sakhtayani from Said ibn Jubayr that Abdullah ibn Abbas said, "Ifsomeone forgets anything of the rituals or omits them intentionally,he must slaughter an animal." Ayyub added "I do not know if he said'Omits' or 'forgets'."Malik said, "If it is a hady that hasto be slaughtered it may only be done in Makka, but if it is asacrifice, it may be slaughtered wherever the one who owes thesacrifice prefers."
USC-MSA web (English) reference: Book 20, Hadith 249
Arabic reference: Book 20, Hadith 946