Is it mandatory to maintain books of account who declare his income under 44ADA?

is it mandatory to maintain books of account in the case of a profession whose gross recepit in the previous year is 4 lakh where he declared his income 3.6 lakh(net profit) out of 4lakh (gross receipt) under 44ADA.

Audit is not necessary but is it mandatory to maintain ledger book, Cash book?

He received both cash and cheque.