He was riding behind the Prophet ﷺ, and he kept reciting the talbiyah until he threw the pebbles at the jamrah.
حدثنا روح حدثنا شعبة عن عامر الأحول عن عطاء عن ابن عباس
أنه كان رديف النبي ﷺ كان يلبي حتى رمى الجمرة
Its isnad is sahih. Amir Ahwal is Amir bin Abdul-Wahid Basri. Ahmad graded him daif, while Abu Hatim and Ibn Hibban graded him reliable. Ibn Main said, "There is no harm in him." In K it reads Asim Ahwal, but it is not clearly written. It used to be read as Amir, then whoever copied it made it closer to being read as Asim. The hadith is a shortened version of the one before it.