Muwatta Malik #476

Yahya related to me from Malik from Yahya ibn Said from Amra bint Abd ar-Rahman that A'isha, the wife of the Prophet, may Allah bless him and grant him peace, said, "If the Messenger of Allah, may Allah bless him and grant him peace, had seen what women do now, he would have forbidden them to go into the mosques, just as the women of the Bani Israil were forbidden." Yahya ibn Said said that he asked Amra, "Were the women of the Bani Israil forbidden to go into the mosques?" and she said, "Yes."