Should one remain silent about injustice from a manager who discriminates in treatment and refuses to pray, or should one complain to higher authorities, given the Hadith: "The one who remains silent about the truth is a mute devil"?

It is not permissible for a manager to allow absence without an excuse. If he treats you according to what the work requires, but treats others with favoritism, this is not an injustice to you. However, if he withholds your right or burdens you with what you cannot bear, then this is an injustice that permits you to complain about him and refer his matter to the authorities, based on the words of Allah Almighty: ﴿Allah does not like the public utterance of evil, except by one who has been wronged.﴾ You must first advise the manager, and if he does not respond, then there is no harm in referring his matter to his superiors, as part of enjoining good and forbidding evil. The saying: "He who is silent about the truth is a mute devil" refers to denouncing evil deeds, not to waiving a personal right. It is advisable to act with wisdom, weigh the benefits against the harms, perform Istikhara (prayer for guidance), and consult trustworthy individuals.