Skandapurana 5.279.6

5.279.6

5 brahmaṇā tathā karaṇe'nujñāyāmadattāyāmapi viśvāmitreṇa triśaṃkoḥ saśarīreṇa svarga- prāptaye svatapaḥprabhāvāddvādaśavārṣikaṃ satraṃ brāhmaṇadvārā samāpya tato'nte'vabhṛtha- snānādikaṃ kṛtvā yajñasamāptikaraṇam. .. 6

5 Even though Brahmā did not give permission to do so, Viśvāmitra, in order for Triśaṅku to attain heaven in his physical body, by the power of his own austerity, had a twelve-year sacrificial session completed through brahmins, and then at its end performed the ritual post-bath ablutions and brought the sacrifice to completion. .. 6