If a bearded man is in grave danger, such as death or torture, is it better for him to remain steadfast and not shave his beard, or to avail himself of the concession and shave it, especially if his parents order him to do so out of fear for him? And would he be sinful for disobeying them in this situation?

Shaving the beard is permissible under duress (ikrah) that is considered valid by Sharia, such as fear for one's life. However, patience and adherence to the stricter ruling (al-azimah) are preferable to taking the concession (ar-rukhsah). Scholars have differed on what is preferable. The followers of Imam Malik believe that taking the stricter path and choosing death is better than taking the concession, whereas the scholars of Iraq hold that if a person is threatened with death or beating, he may do what he is coerced into. If he does not comply and is killed, there is a concern that he might be sinful. If the parents command one to take the concession, their obedience becomes obligatory, as long as it does not involve disobedience to Allah the Almighty.