Does Storing Food In Pots And Pans In The Refrigerator Poison The Food?

My mom used to always tell me to put left overs in a tupperware and place in the fridge. She said the if you put the pot or pan in the fridge to store the left overs, it would poison the food. My boyfriend does this all the time and I’ve always refused to eat the food. Well, now I’m sick and he made some chicken soup. He put the soup in the fridge, in the pot and gave me some for work today. I’m scared to eat it because of what Mom used to always say but I can’t seem to find anything on the net about it. Has anyone heard of this? Is it true that refrigerated food in pots poisons you?