"History of the Song Dynasty"No. 124 biography (biography of Yue Fei 365) records that the bow was cast at the beginning, and it was cast on the back, with four characters of "loyalty to the country" and went deep into the skin.
But I didn't say that these four words were written by my mother-in-law, and they were probably invented by romantic novels later. Yue Fei's filial piety is also recorded in the History of Song Dynasty.