Shiva Purana
प्राणः सप्तदशे चैव विद्धि वर्षं न संशयः ॥ सप्तमासान्विजानीयाद्दिनैः षड्भिर्न संशयः ॥ ५३॥
If it respires for seven days he lives for one year seven months and six days, to be sure.
english translation
prANaH saptadaze caiva viddhi varSaM na saMzayaH ॥ saptamAsAnvijAnIyAddinaiH SaDbhirna saMzayaH ॥ 53॥
hk transliteration by Sanscript