From the Prologue of Ochrid
Sons of the great Prince Vladimir, the baptizer of the Russian people. Before his baptism, Vladimir had many wives and children by them. Boris and Gleb were brothers from the same mother. Before his death, Vladimir divided the state among all his sons. But Sviatopolk, his eldest son, the Prince of Kiev, desired to seize the portions allotted to Boris and Gleb. Therefore he sent men who slew Boris in one place and Gleb in another. These two brothers were extraordinarily devout and pleasing to God in all things, and they met death with prayer and the lifting up of their hearts to God. Their bodies remained incorrupt and fragrant, and were buried in the city of Vyshhorod, where to this day a grace-filled power flows from them, healing people of various diseases and afflictions.
