Revākhaṇḍa ascribed to the Vāyupurāṇa (RKV) 169.3

169.3

yudhiṣṭhira uvāca:
āścaryametallokeṣu yattvayā kathitaṃ mune /
na dṛṣṭaṃ na śrutaṃ tāta śūlasthena tapaḥ kṛtam //

Yudhiṣṭhira said: / This is a wonder among the worlds which has been told by you, O sage! / It has neither been seen nor heard, O dear one, that austerities were performed while on a stake.