Musnad Ahmad 1153:1654

Yahya narrated to us, from Ibn Jurayj, who said: I heard Ibn Abi Mulaykah narrating from Dhakwan Abu ‘Amr, from ‘Aishah, from the Prophet, peace and blessings of Allah be upon him, who said: "Seek the permission of women regarding their private parts." It was said: "But the virgin is shy, so she remains silent." He said: "That is her permission."