He was with Ibn Masud when he threw the pebbles at Jamrat al-Aqaba. Ibn Masud went into the depths of the valley until he came opposite the tree, faced it, and threw seven pebbles, saying "Allahu Akbar" with each pebble. Then he said, "From this very spot, by the One besides whom there is no god, stood the one to whom Surat al-Baqarah was revealed."
أنه كان مع ابن مسعود حين رمى جمرة العقبة، فاستبطن الوادي حتى إذا حاذى بالشجرة اعترضها، فرمي بسبع حصيات يكبر مع كل حصاة، ثم قال: من هاهنا- والذي لا إله غيره- قام الذي أنزلت عليه سورة البقرة.
Bukhari narrated it in Hajj (1750), and Muslim in Hajj (1296), both through Amash who said, I heard Hajjaj say on the pulpit, "The surah in which Baqarah is mentioned, and the surah in which Al Imran is mentioned, and the surah in which Nisa is mentioned." He said, So I mentioned that to Ibrahim, and he said, Abdul-Rahman bin Yazid narrated it to me, and he related it.