Shiva Purana
संवृतः प्रविशेद्योनिं कर्मभिस्स्वैर्नियोजितः ॥ तच्छुक्ररक्तमेकस्थमेकाहात्कलिलं भवेत् ॥ १६ ॥
He enters the womb enveloped and engaged in his own actions. That blood of Venus in one place will become Kalila in one day.
english translation
saMvRtaH pravizedyoniM karmabhissvairniyojitaH ॥ tacchukraraktamekasthamekAhAtkalilaM bhavet ॥ 16 ॥
hk transliteration by Sanscript