"When Abdullah went to stone Jamrat Al-Aqabah, he went to the middle of the valley, faced the Ka'bah, and proceeded to stone the Jamrah at its southern wall. Then he stoned with seven pebbles, saying: "Allahu Akbar" with each pebble. Then he said: 'By Allah except Whom none is worthy of worship. This is where the one stoned to whom Surat Al-Baqarah was revealed.'"
Jami` at-Tirmidhi Book 9, Hadith 94