So during Monopoly, my sister decided not to buy a property and it was auctioned. My brother had no more than $300 and I had around $700. He kept raising the bid even though he couldn't pay and I didn't know since he wasn't showing his money.

He backed out after he made me raise my bid to $550, despite him only having $300, and I lost a lot more money than I had to because he tricked me. Is that legal? It doesn't explicitly say in the rules that you can't trick players by bidding more than you have but it feels illegal to me.

(Edited for clarity)