Janai Purnima Mantra in Nepali

New holy thread ‘janai’ is worn by Hindu males on the occassion of Janai Purnima. 
Here is the mantra to be said: 
जनैपूर्णिमामा नयाँ जनै धारण गर्ने मन्त्र: 

यज्ञोपवीतं परमं पवित्रं प्रजापतेर्यत्‌सहजं पुरस्तात् । 
आयुष्यमग्रयं प्रतिमुञ्चशुभ्रं यज्ञोपवीतं वलमस्तुतेज:।। 

During Janai Purnima, son-in-laws tie the holy thread ‘doro’ in the hands of their in-laws chanting the following ‘mantra’ 

डोरो बाँध्ने मन्त्र: 

येन बद्धो वलीराजा दानवेन्द्रो महावल: ।
तेन त्वां प्रतिबध्नामि रक्षे मा चल मा चल ।।