Vaishnava Samhita. Chaturbhujadasa Charitam. Vol III Book VII Chp 12 Shlokas 1 - 2

श्रीसद्गुरुरुवाच

वैष्णवानां कुले जन्म विष्णुभक्तिप्रदायकम् |

लभ्यते बहुभिः पुण्यैः पूर्वजन्मसमार्जितैः ||

गर्भस्थितानर्भकान् यान् कृपया वीक्षते हरिः |

परीक्षितैव तैनूनं प्राप्यते जन्म वैष्णवम् ||

Shri Sadguru said

The birth as a vaishnava, which enhances devotion for Lord Vishnu is attained by one as a result of the accumulated effect of the merits of many births. Those who are protected by the merciful eyes of Shri Bhagavan, even when they are in the mothers wombs take birth as vaishnavas like Parikshit