and pray for them. Indeed, your prayer is a source of comfort for them.” [al-Tawbah: 103]
Its permissibility is contingent upon explicit permission or a contextual indication. If he knows that there is a reprehensible act there which he is able to change, he attends and changes it; otherwise, he declines.
His statement, “A person observing a voluntary fast breaks it if it will please [the one who invited him],” means that one observing a voluntary fast—such as the fast of the White Days, Monday, Thursday, six days of Shawwal, the first ten days of Dhu al-Hijjah, Ashura, and the like—accepts the invitation. But should he break his fast or not? The author mentioned a distinction: if breaking his fast will please the inviter and bring him joy, then he should break it. If it will not please him—for example, if the inviter does not care whether he eats or not, and what matters to him is simply that he accepts the invitation—then it is preferable that he not break his fast but complete it. This is because his fast is voluntary, and one should not discontinue a voluntary act of worship except for a sound reason.
His statement, “Eating is not obligatory,” means that it is not obligatory for the invited person to eat; rather, only attendance is obligatory, due to the Prophet’s words, may Allah bless him and grant him peace: “If one of you is invited, let him respond; if he wishes, he may eat, and if he wishes, he may refrain.” (1) This hadith indicates that eating is not obligatory, whereas the previous hadith indicates that it is obligatory, in the words: “Let him eat.” How are the two hadiths to be reconciled?
They may be reconciled by saying that the choice applies when abstaining from eating entails no harm. But if it does entail harm, then there is no doubt that eating is obligatory. For instance, a man prepares a banquet of one sheep, two sheep, or more, makes the necessary preparations, and invites people to eat; then they say, “We are not obligated to eat, and we are not going to eat!” This is objectionable, in view of the Prophet’s words, may Allah bless him and grant him peace, to a man who had withdrawn to one side away from the people and said, “I am fasting.” The Messenger of Allah, may Allah bless him and grant him peace, said: “Your brother invited you and went to effort for you. Eat, then fast a day in its place