I saw the Messenger of Allah ﷺ throwing the pebbles at the Jamarat with stones the size of those used in the flicking game.
أخبرنا محمد بن بشار قال حدثنا يحيى عن ابن جريج عن أبي الزبير
رأيت رسول الله ﷺ يرمي الجمار بمثل حصى الخذف
Muslim narrated it in the Book of Hajj, chapter on the recommendation that the pebbles for the jamarat be the size of pebbles used for flicking, hadith no. 1299, from the hadith of Ibn Jurayj, through him. It is also found in Kubra, hadith no. 4081.