Musnad Ahmad 1153:1700

Waki’ narrated to us, Isra’il narrated to us, from Ibrahim ibn Muhajir, from Yusuf ibn Mahak, from his mother Musaykah, from ‘Aishah, who said: We said, "O Messenger of Allah, shall we not build a house for you at Mina that will shade you?" He said, "No. Mina is a place of encampment for whoever arrives first."