I saw the Messenger of Allah (ﷺ) throwing pebbles on the day of sacrifice while on his riding beast in the forenoon, and next when the sun had passed the meridian.
Sunan Abi Dawud Book 11, Hadith 251
← Previous Hadith I saw the Messenger of Allah (ﷺ) throwing pebbles on the day of sacrifice while on his riding beast and saying: Learn your rites, for I do not know whether I am likely to perform Hajj after this occasion.

Sunan Abi Dawud Book 11, Hadith 250 Next Hadith → I asked Ibn 'Umar: When should I throw pebbles at the jamrah? He replied: When your imam (leader at Hajj) throws pebbles, at that time you should throw them. I repeated the question to him. Thereupon he said: We used to wait for the time when the sun passes the meridian. When the sun declined, we threw the pebbles.

Sunan Abi Dawud Book 11, Hadith 252