Musannaf Ibn Abi Shayba 3:5239

Waki’ narrated to us, [he said] Sufyan ibn al-Mughirah narrated to us, from Humayd ibn Hilal, from Abu al-Ahwas, who said: Abdullah said: The woman is an 'awrah (a private/intimate part), and she is closest to her Lord when she is in the depth of her house. So when she goes out, the devil seeks to gaze upon her.