Is adopting the idea of a commercial project created by another person and implementing it without their permission considered theft of their effort, and what is the legitimate Shar'i way to avoid that?

The answer differentiates between three scenarios:

1. If the idea is a well-studied project for which effort or money has been expended, then it is impermissible to infringe upon it, attribute it to someone other than its owner, or execute it without his permission. The right of invention is recognized and holds monetary value.

2. If it is merely an idea or a title without study or effort, then it is permissible to benefit from it, and its execution is not considered an infringement. It is commendable to offer partnership to its originator if the matter is among friends.

3. If it is a private project kept secret from people and mentioned to a close associate in a private setting, then it is not permissible for this trusted person to divulge the secret or execute the project without its owner's permission, unless it is known that the owner has abandoned the idea or is unable to execute it.