It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "All of Muzdalifah is a place of standing, and pass quickly through Batn Muhassir, and it is binding on you to use pebbles the size of small stones (for stoning)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12147