ANSWER:

He should learn from his previous mistakes! The Prophet salla allahu alaihi wa sallam said: a believer is not stung from the same hole twice.

It is said: if you fool me once, shame on you. But if you fool me twice, shame on me!

He must consult others whom he trusts before acting and trusting people with his money! He must also get everything documented and with witnesses so that he can take them to court if necessary. 

Sheikh, my father has a habit of getting played out by people that he does business with. The problem is partly because, he over trusts them, wants to be revered by them & doesn’t say no. He has lost a lot of money as a result, yet never learns a lesson. Please tell me what is a good advice to give him, perhaps from a hadeeth or life lesson from Prophet Muhammed or a Sahaba.