When it is not possible to recommend the truth and prevent badness because of the fear that harm is caused for oneself or others, dissembling-mudara- is remaining silent to prevent mischief. While a person wants to prevent badness in the heart, remaining silent is religiously allowed. Even it brings the merit of alms. One should have soft words and pleasant manner while dissembling. During the lesson a teacher may dissemble against students.
Imam Gazali says: “People are of three groups: Some of them are like nourishment. They are necessary for everybody and all time. The second group is like medicine. The need for them is felt from time to time. Some of them are like illness. People do not need them. But they worry people and pester them. One should do dissembling to avoid them.” This behavior is allowed and sometimes it is canonically laudable.
A visitor came before Our Prophet-May Allah commend and salute him-. He declared: “Let him come. He is an evil person” But when he came inside he talked him with merry and pleasant words. After the leaving of man when people asked that why he spoke him softly he said: “The person who will be in the worst place in doomsday is the one who is treated kindly and shown honor to avoid his harm”
Again in a hadith it is declared: “It is allowed to make gossip about the person who commit sins without shame, it is also permitted to dissemble against them for being safe from their harm. But this behavior shouldn't turn to be flattery”
“Mudara” is to pay from the gains of this world to protect religion and world from harm. But flattery is making sacrifice from religion in order to attain worldly profits. While dissembling against a cruel person he and his oppression are not approved. (1)
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