Amr bin Mnswr al-Nsa'iy عمرو بن منصور النسائي أبو سعيد · The Book of Funerals

"I heard the Messenger of Allah say: 'When you see the dead, say something good, for the angels say Amin to whatever you say; When Abu Salamah died, I said: 'O Messenger of Allah, what should I say?' He said: 'Say" Allahummaghfirlanaa wa lahu wa a 'qibni minhu 'uqbai hasanah (O Allah, forgive us and him, and compensate me well for this loss.)"' Then Allah, the Mighty and Sublime, compensated me with Muhammad."

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