As long as you have accepted the sale consideration or Advance for sale of house in good faith, you shall not come to harm as you are not supposed to know the source from which he has paid the sum.
Is he related to you closely? Is he a colleague of yours? No information on this.If you are not one them, most probably you will not come to trouble. However, if it can be proved that just to stash away ill gotten money this agreement/sale deed is created, you will be in trouble. This is to say that if you are not involved at all and you entered into the agreement and received the money in good faith, without any least possibility of your knowing the source of the money being paid to you, you will not come to harm legally. But the investigative agencies may call you for giving your statement and may grill you.