A brother has stolen from me but has not sought forgiveness, only lowering his head. What is best for me from a Sharīʿah perspective? Is it Sunnah and more virtuous for my ākhirah to forgive him, or not?

Ustadh AbdulAziz al-Haqqan

If forgiveness fixes the brother and make him quit and regret by the will of Allah, yes, if it makes him transgress more then no.