It was narrated that Anas bin Malik said:
“What the Messenger of Allah ﷺ most enjoined when he was dying and breathing his last was: The prayer; and those whom your right hands possess.”

حَدَّثَنَا أَحْمَدُ بْنُ الْمِقْدَامِ، حَدَّثَنَا الْمُعْتَمِرُ بْنُ سُلَيْمَانَ، سَمِعْتُ أَبِي يُحَدِّثُ، عَنْ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَتْ عَامَّةُ وَصِيَّةِ رَسُولِ اللَّهِ ﷺ حِينَ حَضَرَتْهُ الْوَفَاةُ وَهُوَ يُغَرْغِرُ بِنَفْسِهِ " الصَّلاَةَ وَمَا مَلَكَتْ أَيْمَانُكُمْ " .