Where did the Ababil birds throw the stones upon Abraha's army in Mecca?

When Abraha and his army reached the valley of Muhassir, the elephant knelt and refused to advance towards the Kaaba. It is said that Nufayl ibn Habib al-Khath'ami took hold of the elephant's ear and said to it, "Kneel, Mahmoud, for you are in God's sacred land." So the elephant knelt. They tried to direct the elephant towards different directions, and it would trot, but when they directed it towards Mecca, it would kneel. At that point, Allah sent upon them flocks of birds (Ababeel) from the sea, each bird carrying three small stones. Whoever was struck by these stones had their limbs torn apart and perished, so they fled. The valley is called "Wadi Muhassir" because the elephant was "hussira" there, meaning it became exhausted and stopped moving.