Is it safe to Buy land for ourself by giving full amount to seller for power of attorney

We had land agreement with seller that we are giving this much of amount now for land and later we will give you complete money at the time of sale deeds/property registration. Now as sale deeds registry process is taking time here and he is in hurry, he is forcing us that you can take power of attorney for that land by giving him complete amount now itself and later you can make property registration in your name. 1. Is it safe to give him complete amount by making just power of attorney? 2. what if after getting money he will try to revoke the power of attorney? is it possible ? 3. I understand that in case of his death, bankruptcy and mental illness this power of attorney will be invalid? kindly confirm? 4. After getting power of attorney, can i transfer the land to my name by sale deeds/property registration? is it legal to do so? my main focus is whether it is risk to give him full amount for power of attorney and later can i successfully convert it to my name legally without any issues. we want to purchase for ourself only and not to sell any one else. please help me here, i am really tensed. Thank you very much, Chetan Madhya Pradesh