He was present at the Eid prayer with the Messenger of Allah ﷺ. The Prophet prayed and then delivered the sermon, saying, "Whoever slaughtered before performing the prayer should slaughter another in its place." On another occasion he said, "Let him slaughter again, and whoever has not yet slaughtered, let him slaughter in the name of Allah."
حدثنا عفان حدثنا شعبة أخبرني الأسود بن قيس قال
أنه شهد العيد مع رسول الله ﷺ صلى ثم خطب فقال من كان ذبح قبل أن يصلي فليعد مكانها أخرى وقال مرة أخرى فليذبح ومن كان لم يذبح فليذبح باسم الله
Its isnad is sahih. It is found in Bukhari, in the book of oaths, 11/550, no. 6674 (Fath al-Bari), and Muslim, 3/1551, no. 1961, in the book of sacrifices, and Ibn Majah, 2/1053, no. 3152, and Humaydi, 2/341, no. 775.