Prime Minister Narendra Modi has penned a emotional letter to India's former President Pranab Mukherjee, whose term ended on July 25.

 In the letter, Modi addresses Mukherjee as 'Pranab da', an expression which is close to Mukherjee's mother tongue Bengali and directly translated to an "elder brother".

Prime Minister acknowledged Mukherjee's "immense contribution" during his five-year Presidential term and his role as a "father figure and mentor" at the begining of Modi's tenure in 2015.

See how Pranab Mukherjee's Posted the letter on his twitter account:

On my last day in office as the President, I received a letter from PM @narendramodi that touched my heart! Sharing with you all. pic.twitter.com/cAuFnWkbYn

— Pranab Mukherjee (@CitiznMukherjee) August 3, 2017

Modi also praised Mukherjee's intellect called him a 'repository of knowledge'. He also said that Mukherjee's courtesy towards him would act as a source of inspiration.

In the last part of the letter, Modi thanked Mukherjee and congratulated him on his successful five-year tenure which led India to the path of development. He wished Mukherjee best for his future endeavours and said that Mukherjee's 'legacy will continue to guide us'.