Prophet (SAW)'s Prayers When death is eminent

Recite:

اللَّهُمَّ اغْفِرْ لِي وَارْحَمْنِي وَأَلْحِقْنِي بِالرَّفِيقِ الْأَعْلَى

"O Allah, forgive me and have mercy on me and let me reach the Companion on high". (Hisnul Hasin)