(used as a wish to s.o. who has died) may s.o. lie peacefully: мир праху X-a - may X rest in peace
God rest X's soul.
Так завершила свои дни пани Янжвецкая. Достойная, гордая оказалась женщина. Мир праху её! (Рыбаков 1). That's how Madame Yanzhvetska ended her days. She had been a proud and worthy woman, may she rest in peace (1a).