Hazrat Mahdi (as) knows what is lawful (halal) and unlawful (haram)

Hussain (ra) was asked: “By what signs will Hazrat Mahdi (as) be known?” He replied: “By his ease of heart and dignity, by his knowing what is lawful and what is unlawful.” (Mari’ bin Yusuf Karami Hanbali, Fawaid Fawaid al-Fikr fil Mahdi al-Montazar)