In any event, a woman’s being alone with a man in a car when he is not one of her unmarriageable relatives is in itself objectionable; yet you still do not know—she may in fact be related to him.
The point is that you must have sure knowledge: you must know that a certain act is indeed something enjoined, or that another act is truly forbidden; and you must know that the person before you has actually neglected the duty or committed the wrong before you intervene.
The third condition: forbidding an evil must not result in an evil that is even worse and more serious. Consider this illustration: you come across a person who is smoking. Smoking is unquestionably unlawful, a reprehensible act that ought to be condemned. However, if your censure would drive him to drink wine—so that he leaves, heads for the liquor sellers and consumes alcohol—then you do not forbid him his first wrongdoing, for that first wrongdoing is the lesser of the two. When one is forced to choose between two harms, it is obligatory to opt for the lesser.
The proof for this condition is the Almighty’s statement: “And do not insult those they invoke besides Allah, lest they insult Allah in enmity without knowledge” (Qur’an 6:108). Cursing the idols of the polytheists is, in principle, something required by the Law, and we are indeed obliged to denounce the deities of the polytheists, to denounce the festivals of the unbelievers, to warn against them, and never to approve of them. We must also alert our ignorant, rash brothers and sisters that it is impermissible to share in the festivals of the disbelievers, for approving of unbelief may well drag one into unbelief—Allah’s refuge is sought. Would you be content to see the rites of unbelief observed and then take part in them? No Muslim would ever accept that. For this reason Ibn al-Qayyim—one of the eminent disciples of Shaykh al-Islam—said that anyone who joins the unbelievers in their festivals and congratulates them on those occasions, even if he does not fall into outright disbelief, has without a doubt committed a prohibited act. He spoke the truth, may Allah have mercy on him. Accordingly, we are duty-bound to caution our fellow Muslims