Shiva Purana
आत्मानं च पृथङ्मत्वा प्रेरितारं ततः पृथक् ॥ असौ जुष्टस्ततस्तेन ह्यमृतत्वाय कल्पते ॥ ७ ॥
Realising distinction between him and himself and being gratified after resorting to him Paśu can attain immortality.
english translation
AtmAnaM ca pRthaGmatvA preritAraM tataH pRthak ॥ asau juSTastatastena hyamRtatvAya kalpate ॥ 7 ॥
hk transliteration by Sanscript