From Sahih Muslim (Hadith 3137):
Jabir (Allah be pleased with him) reported:I saw Allah's Apostle (ﷺ) flinging pebbles while riding his camel on the Day of Nahr, and he was saying: Learn your rituals (by seeing me performing them), for I do not know whether I would be performing Hajj after this Hajj of mine
Reference: Muslim 3137