Ibn 'Abbas (RAA) narrated, "The Messenger of Allah (ﷺ) slaughtered a ram for both al-Hasan and al-Husain (at their birth).' Related by Abu Dawud, Ibn Khuzaimah, Ibn al-Garud and 'Abdul Haqq graded it as Sahih. (ID)
English reference (ID): Book 12, Hadith 1396 (ID)
Arabic reference (ID): Book 12, Hadith 1355 (ID)