He saw the Prophet ﷺ slaughtering his sacrificial animal with his own hand, saying the takbir over it.
حدثنا عفان حدثنا أبان حدثنا قتادة
أنه رأى النبي ﷺ يذبح أضحيته بيد نفسه ويكبر عليها
No references are available.
Its isnad is sahih, mentioned previously at 13356.