Sale price of property

your welcome for  response

If the transaction (receipt of 6 lacs) has not been carried through bank, then can 4 lacs be considered as sale consideration?

Here the querist has specifically mentioned that the property is sold for 6 lacs. So in that case, 6 lacs can ONLY be the sale consideration whether received in cash or through bank. Further, accepting cash would lead to violation of provisions of section 269SS and 100% penalty will be levied.

So in the above scenario, I don't think considering 4 lacs as sale consideration is legally correct.

According to me ₹600000 shall be considered as Sale consideration. If ₹4,00,000 is taken as sale consideration then Rs 200000 would be considered illegal.