Shiva Purana
शिरोहीनं यदा पश्येत्षड्भिर्मासैर्भवेत्क्षयः॥ समस्तं वाङ्मयं तस्य योगिनस्तु यथा तथा॥ ८॥
If he finds the shadow-person headless, the entire power of oral expression of practising Yogin becomes eliminated within six months.
english translation
zirohInaM yadA pazyetSaDbhirmAsairbhavetkSayaH॥ samastaM vAGmayaM tasya yoginastu yathA tathA॥ 8॥
hk transliteration by Sanscript