Zhang Chi's words instantly shifted the pressure onto Yi Ran.
Heavenly oaths are not given lightly. Even mortals fear divine retribution, let alone cultivators pursuing the Dao.
Under normal circumstances, Zhang Chi wouldn't have been able to force Yi Ran to swear an oath.
Cultivators avoid such things, even if they are truly innocent, they are not willing to prove themselves with an oath.
Unless there is no other way, they would only plea Lord of Heaven for help.
If it were so simple, everyone could just ask potential traitors to swear an oath. Whoever is not willing to swear would be considered the traitor, and everything would be easy.
Unfortunately, things can't be handled that way.
Others won't agree to swear an oath without evidence, so why should they?
Moreover, Zhang Chi is a junior, and he couldn't force anyone to do anything.