What is the governing principle for a legal agent to manage the properties of their principals and collect rents from them, while considering leniency towards tenants, developing the principals' wealth, and preserving it?

The agent is trustworthy and is not permitted to act except in ways that benefit the principal. If the agent does something that harms the principal, then he is liable to compensate for the damage if he exceeded his authority or was negligent. Therefore, it is not permissible to waive any right or property to tenants without the principal's permission. The tenant is not liable for damage occurring in the house unless it resulted from negligence or exceeding bounds. It is not permissible to take payment for work except by agreement with the principal, for agency is permissible with or without a fee, according to the agreement, unless the agent is poor, in which case he may consume an amount commensurate with his efforts.