Musannaf Ibn Abi Shayba 21:661

Abu al-Ahwas narrated to us, from Tariq, from Sa'id ibn al-Musayyib, who said: 'Umar used to say regarding the prayer over him (the deceased): If it was evening, he would say: "O Allah, Your servant has entered the evening, and he has departed from the world and left it for its people, and You have become free of need for him, while he has become in need of You. He used to testify that there is no god but You, and that Muhammad is Your servant and Your messenger, so forgive his sins." If it was morning, he would say: "O Allah, Your servant has entered the morning, and he has departed from the world and left it for its people, and You have become free of need for him, while he has become in need of You. He used to testify that there is no god but You, and that Muhammad is Your servant and Your messenger, so forgive his sins."