Implications of lump sum amount credited to saving bank account

where did this come from, source>??

Thanks for reply

It comes from retirement proceeds, which are invested in post office MIS

if source of principal is confirmed and tax paid, and interest is also tax paid or deemed to be  tax paid, then no issue, 

in case of any query from department, the assesee has to produce the records and establish that these savings were made from tax paid income in past and interest accured were also offered for tax purpose in the year of accural