The Messenger of Allah ﷺ addressed us while we were at Mina, and our hearing was opened so clearly that we could hear what he said even while we were in our tents. He began teaching them the rites of pilgrimage, and when he reached the matter of the stone-pillars, he held up his two index fingers and said, "With pebbles the size of those used in flicking."Then he ordered the Muhajirun to camp in the front area of the mosque, and ordered the Ansar to camp behind the mosque, and the rest of the people settled after that.
خطبنا رسول الله ﷺ ونحن بمنى ففتحت أسماعنا حتى كنا نسمع ما يقول ونحن في منازلنا فطفق يعلمهم مناسكهم حتى بلغ الجمار فوضع أصبعيه السبابتين ثم قال: بحصى الخذف. ثم أمر المهاجرين فنزلوا في مقدم المسجد، وأمر الأنصار فنزلوا من وراء المسجد، ثم نزل الناس بعد ذلك.
Narrated by Abu Dawud (1957), Nasai (2996), Imam Ahmad (16589), and Bayhaqi (5/127), all of them from the hadith of Muhammad bin Ibrahim Taymi, from Abdul-Rahman bin Muaz Taymi, who said (then he mentioned the hadith). See its full referencing in the chapter on the sermon of the Prophet ﷺ during the Farewell Pilgrimage.