the Messenger of Allah ﷺ had told them of the death of an-Najāshī, the ruler of Ethiopia, on the day that he died, and he said: "Pray for forgiveness for your brother."  

أَنَّ رَسُولَ اللَّهِ ﷺ نَعَى لَهُمُ النَّجَاشِيَّ صَاحِبَ الْحَبَشَةِ الْيَوْمَ الَّذِي مَاتَ فِيهِ وَقَالَ اسْتَغْفِرُوا لأَخِيكُمْ