Matsya Purana 183.85

183.85

vāmāṃguṣṭhanakhāgreṇa chinnaṃ tasya śiro mayā.
brahmovāca.
tadā niraparādhasya śiraśchinnaṃ tvayā mama .. 183.85 ..

Mahâdeva—In the days of yore Lord Brahmâ had five heads and the fifth one was shining like gold Once Brahmâ said to Me 'I know thy genesis,' when I angrily cut off His fifth head with the nail of my left toe Then Brahmâ said 'Thou hast beheaded Me without any fault and through My curse thou shalt bear a skull as the badge of the sin of inflicting injury on Brahmâ Thou shalt roam about in the sacred places'—81-86