Hazrat Abdullah bin Rafi' narrates that Hazrat Umm Salamah was having a Mushaf written, and when she reached this verse { حَافِظُوا عَلَی الصَّلَوَاتِ وَالصَّلاَۃ الْوُسْطَی } (Be watchful of the prayers, and especially the middle prayer), she said: Write that by this is meant the Asr prayer.