Šimon would live in Kievan Rus' for the rest of his life, and he first served Yaroslav I the Wise and later his son. In 1068, he joined Yaroslav's three sons in the Battle of the Alta River against the Polovtsians. It is reported that before the battle, saint Anthony of Kiev, predicted a dire outcome for the battle, but he also predicted that Šimon would be saved through a miracle. Šimon survived the battle, but he was severely wounded. Anthony took care of Šimon and healed his wounds. In recognition, when Anthony founded the cave monastery, Šimon donated a belt and a wreath of gold that his father Afrikan had used to adorn a crucifix. The gifts were worth 50 gold grivnas. The Varangian was probably one of the first to be buried in the monastery and he was the first one to receive a written remission from the monastery that both he and his descendants were pardoned for all their sins.