This is under South African law.
First, some background. Said "tenant" bought the house and is currently paying occupational rent to stay there until the property transfer has been finalized. I'll refer to them as the "future owner".
Initially, the future owner agreed to accommodate some furniture while the current owner gets them sold. Some time later the only item left was a large wall unit. The future owner gave notice that they wanted to start doing some building alterations, and the wall unit needed to be out of the way by a specified date. The current owner neglected to remove the wall unit. A few days after the agreed date of removal, the future owner put the wall unit outside, and it got destroyed in the rain (we are currently in the rainy season).
The question then is: who should be held responsible for the damage (wall unit cost) and disposal?