"ومع أنه كان غير موثوق، كن مجتهدًا"

Simplified Meaning:

If someone is unreliable, you should still be careful and work hard. Imagine you are working with someone who often forgets important things or doesn't always do what they promise. You can't control their behavior, but you can control yours. By being diligent, paying attention to details, and making sure everything is done correctly, you can try to prevent problems that might arise from their lack of reliability. For example, if you have a group project at school and one member never does their part, you can step up by double-checking their work or picking up the slack to ensure the project is completed well. This teaches us that our own actions and diligence are important, even when others are not as dependable.