Complex sentence: That's why in the famous story of Rostam's fight against Esfandyar, a simorgh warned Rostam before helping him to defeat the Prince that prince Esfandyar was a blessed divine prince and there would be no shame in surrendering to him.
Split into simpler sentences: That's why in the famous story of Rostam's fight against Esfandyar, a simorgh warned Rostam before helping him to defeat the Prince that prince Esfandyar was a blessed divine prince. He told Rostami that there would be no shame in surrendering to him.