I say, and with God's success: The prohibition is established by her testimony if she is chaste or if he is strongly inclined to believe her truthfulness. However, if she is immoral and her truthfulness is not strongly believed, such as when she is not in her menstrual period, her word is not accepted. This is the essence of what Ibn Najim has clarified as mentioned in Manhal al-Waridin, page 146. And God knows best.