Sayyiduna Abd al-Rahman bin Mu'adh al-Taymi (may Allah be pleased with him) said: When we were at Mina, the Prophet (peace and blessings be upon him) addressed us. (The narrator) said: Our ears were opened, so that we could hear what he (peace and blessings be upon him) said while we were in our own places. (The narrator) said: He (peace and blessings be upon him) began teaching us the rites of Hajj until he came to the Jamrahs, and he (peace and blessings be upon him) said: "Small pebbles," and he (peace and blessings be upon him) placed his two index fingers one on top of the other. And he ordered the Muhajirun: "Alight at the front of the mosque," and said of the Ansar: "Let them alight behind the mosque." Then after that the rest of the people alighted.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9538