अनन्य भक्तहृदयाय नमः

Mantra NO. 12 from "Shree Namratnakhya Stotra" is:

अनन्य भक्तहृदयाय नमः 

ananya bhaktahRRidayAya namaH 

The explanation of the Mantra is very beautiful and dwells on the feeling of harmony (ऐक्य) and intimacy (आत्मीयता) between Bhagavan Shree Krishna and a bhakta, please see the following Tika in Hindi:

Cited from "SHREE NAMRATNAKHYA STOTRA"

 #Shree RaghuNathaLala Rachita#, 

Sanskrit-Hindi - LINK to PDF-SCAN