The Messenger of Allah ﷺ led us in the 'Asr prayer at (the place known as) Mukhammas, and then said: This prayer was presented to those gone before you, but they lost it, and he who guards it has two rewards in store for him. And no prayer is valid after till the onlooker appears (by onlooker is meant the evening star). (Using translation from Muslim 830a)
صَلَّى بِنَا رَسُولُ اللهِ ﷺ الْعَصْرَ بِالْمَحْمَصِ وَقَالَ إِنَّ هَذِهِ الصَّلَاةُ عُرِضَتْ عَلَى مَنْ كَانَ قَبْلَكُمْ فَضَيَّعُوهَا فَمَنْ حَافَظَ عَلَيْهَا كَانَ لَهُ أَجْرُهُ مَرَّتَيْنِ وَلَا صَلَاةَ بَعْدَهَا حَتَّى يَطْلُعَ الشَّاهِدُ وَالشَّاهِدُ النَّجْمُ لَفْظُ حَدِيثِ قُتَيْبَةَ