لاَ صَلاَةَ بَعْدَ صَلاَةِ الْعَصْرِ حَتَّى تَغْرُبَ الشَّمْسُ وَلاَ صَلاَةَ بَعْدَ صَلاَةِ الْفَجْرِ حَتَّى تَطْلُعَ الشَّمْسُ "
Abu Sa'id al-Khudri reported Allah's Messenger (ﷺ) as saying: No prayer is valid after the 'Asr prayer till the sun sets and no prayer is valid after the dawn prayer till the sun rises.