Skandapurana 7.20.13

7.20.13

brahmaṇo'nurodhāt tacchiraḥkapālamādāya vikṛtarūpaṃ dadhato rudrasya devaveśmasu bhikṣārthaṃ pracāraḥ, viṣṇoḥ sakāśād bhikṣāmādadānena rudreṇa kapālavartini bhaikṣarase viṣṇośchāyādarśanāttatsadṛśamūrtternarasya sarjanam .

At the request of Brahmā, Rudra, taking the skull of that head and assuming a deformed form, wanders about the dwellings of the gods for alms; while receiving alms from Viṣṇu, Rudra beholds the reflection of Viṣṇu in the alms-broth resting in the skull, and from that creates Nara whose form resembles him.