Skandapurana 5.268.55

5.268.55

tato viśvāsamāyā taṃ jahi vajreṇa dānavam..
ṣaḍupāyai ripurvadhya iti śāstranidarśanam..55..

Then, when he has gained confidence, slay that Dānava with your thunderbolt! / 'An enemy should be slain by the six means'—such is the precept of the treatises.