Skanda Purana 4.82.224

4.82.224

na balena hatāḥ saṃkhye hatā evacchalena hi .. 4.2.82.110 .
baliṃ pātālamanayastvaṃ nṛvāmanatāṃ dadhat ..

they were not killed by strength in battle, but were indeed killed by trickery! / You sent Bali to Pātāla by assuming the state of a human dwarf;