What is the word engraved on the sword of Purple Clothes Hou in Lu Xiaofeng legend?

The word "heaven and earth repeatedly" comes from the Taoist Yin Fu Jing, "Heaven kills, and the stars move easily; Murderous look, land of dragons and snakes; People are killing people, and heaven and earth are repeating. Corresponding to the meaning of the magic sword "killing people". In other words, Hong Kong and Taiwan films still pay great attention to details and the connotation of traditional culture.