Musannaf Ibn Abi Shayba 8:1480

Abu Bakr narrated to us, he said: Kathir ibn Hisham narrated to us, from Ja'far ibn Burqan, he said: Al-Walid ibn Dinar informed me, from Nafi', from Ibn Umar, that when he would stone the Jamrah, he would move forward in front of it. Then he would supplicate to Allah and raise his hands, and we would raise [our hands] with him. He would not lower his hands until he would say "Allahu Akbar," and we would lower our hands while he remained as he was.