I brought some assets from my friend and Can I use it for my game??
He had purchased that but we both are using it .And our Games are different.Will it be illegal if I use it??
Yes, that is illegal. Your friend can’t be reselling someone else’s work.
How much do you want to bet that his friend that has sold him these assets doesn’t even exist; that Xummatul invented him and the whole ‘I bought them off him’ scenario to try and alleviate suspicion from falling on him that he has actually gone to one of the sites/torrents whatever and has stolen, downloaded them himself and is using them in his project?
Well what I would do is not post stuff like this at all. No one will find out that you have an illegal copy if you don’t make posts on the forums about it. Just some advice 
giggles like an evil schoolgirl