I heard the Messenger of Allah ﷺ say: One of you who believes in Allah and in the Last Day should not raise her head until the men raise their heads (after prostration) lest they should see the private parts of men. (Using translation from Abū Dāʾūd 851)
رَسُولَ اللهِ ﷺ يَقُولُ مَنْ كَانَتْ مِنْكُنَّ تُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخَرِ فَلَا تَرْفَعْ رَأْسَهَا حَتَّى يَرْفَعَ الرِّجَالُ رُءُوسَهُمْ كَرَاهِيَةَ أَنْ يَرَيْنَ مِنْ عَوْرَاتِ الرِّجَالِ