Shiva Purana

siva.sh/siva-purana/saturda-samhita/16/15

शंभुस्तन्मतमाज्ञाय तच्छिरांस्यच्युतेन ह ।। पुरा छिन्नानि वै केतुसंज्ञानि निदधे गले ।। १५।।

sanskrit

Realising his desire, Śiva fixed on to his neck his head that had been formerly cut off by Viṣṇu, and that was known as Ketu.

english translation

zaMbhustanmatamAjJAya tacchirAMsyacyutena ha || purA chinnAni vai ketusaMjJAni nidadhe gale || 15||

hk transliteration by Sanscript