that's a mistake you may regret for very long.
It is your bank statement of account which is part of your Income Tax returns (FBR).
in order avoid friction / heart burn with your friend, get your bank statment and ask him to take you along to the leasing bank. There you can meet the person handling the documentation cross check every document ask him to fill out sign and put date on it, get the copy of documents.
Walk away if they ask for your CNIC along with bank statment with sign documents. - That means your friend is trying to con you with help of leasing bank to get vehicle under your cnic & bank statment., and surely he has some criminal intentions.
If there is some hanky panky by the leasing bank to provide you copy or your friend want you to sign a blank document simply decline. You may lose a friend but you will not get haunted by Bank & FBR hawks.
- that sounds rude some of you may feel it highly arrogant suggestion but .. Mr. Mubasher Munir will be in safe corner to take exit if he feel there is some smoke.