What are the general principles for the commendation of men in Islamic law, specifically concerning Islamic work?

Assuming leadership positions depends on two pillars: strength and trustworthiness. The most competent in both aspects is preferred. If there is a deficiency in one of them, the most suitable is preferred according to the needs of the position. Strength in war means courage, experience, and ability to fight, while trustworthiness means fearing Allah and not fearing people. The strong transgressor is preferred in war over the trustworthy weak person, as the Prophet, peace and blessings be upon him, did with Khalid ibn al-Walid. He also forbade Abu Dharr from leadership due to his weakness, despite his truthfulness, because the most suitable for every leadership position is the one most capable of it, even if they are less virtuous in other aspects.