Humans dying was ineffable. Aziraphale had always known this. He just hated it when it happened to humans he had genuinely enjoyed watching grow in their leadership and come into their own. He could not believe this was the same baby he once rescued from being slaughtered by the Egyptians. It had really been so long.
Moses knew this too. He was sad to leave his people and Aziraphale would make sure he knew his impact on the world and the people here.
Moses wrote the most beautiful psalms. Psalms that would be read all over the world in the future. He also wrote a beautiful summary of his people's history only instilling the fact that he truly did love and care for the people he had lead. He also put up a recapitulation of the law because he wanted to make sure the society they had made did not crumble to pieces and chaos in his permanent absence. He wrote a beautiful song and blessed the tribes and provided further blessings upon the Earth.
When his time came Aziraphale sang for him and mircled the pain away. His song brought comfort to his soul and calmed his spirit. He stayed with him until the life vanished and Azreal and Death were there to collect. Azreal once again failed to see why Aziraphale was so attached to the humans while Death remained a silent observer as he always was. Never judging. Always watching.
God then commissioned Joshua to be the next leader of the people. Strap in. It's going to be wild ride folks.