He was riding behind the Prophet ﷺ, and he kept reciting the talbiyah until he threw the pebbles at the Jamrah.
أخبرنا حميد بن مسعدة عن سفيان وهو ابن حبيب عن عبد الملك بن جريج وعبد الملك بن أبي سليمان عن عطاء عن ابن عباس
أنه كان رديف النبي ﷺ فلم يزل يلبي حتى رمى الجمرة
Reported by Bukhari, chapter on talbiyah and takbir on the morning of the sacrifice until he throws at the Jamra, hadith no. 1685, and Muslim, Hajj, chapter on the recommendation for the pilgrim to continue the talbiyah until he begins throwing at Jamra Uqba on the day of sacrifice, hadith no. 1281/267, from the hadith of Ibn Jurayj on this same account, and it is also in Kubra, hadith no. 4061.