What is the ruling on one who bears the difference in the equipment's value after it decreases from the value estimated for it at the time of partnership, knowing that its maintenance was paid by the company?

This contract is a type of partnership involving assets (ʿurūḍ), which is considered invalid by most scholars. However, it is deemed valid by a group of scholars if the assets are appraised at the time of the contract.

According to the view that considers it valid, the equipment and cash become a single asset for the partnership. Each partner bears a share of the work proportional to their capital contribution.

The owner of the asset (ʿarḍ) is not harmed by a decrease in its price nor benefits from an increase in its price after the contract. Maintenance of the equipment is paid from the partnership’s funds.

If you appraised the equipment and intended a partnership regarding it, then you are partners in it, and none of you has exclusive ownership of it.

However, if your intention was for the partner to own the equipment and for it to remain their responsibility, then the contract is invalid and not a partnership.