Once Brahmadev organized a massive yajna and invited all the Gods and Rishis. Later when Daksh Prajapati entered the arena everyone stood from their seats to greet him, except for Brahmadev and Bhagwaan Shankar.
Brahmadev was Daksh's father. But when Shankar ji did not stand up, Daksh prajapati took offence. In order to take revenge, he organized a Daksh Yajna and deliberately did not invite Shiv ji and Sati for the same.