May Allah not make your trade profitable, for mosques were not built for this purpose.” (1) This is so that he may be excused.
His statement, “Otherwise, he should decline”: is this obligatory or merely permissible? It is obligatory, so long as he knows that there is an evil present and is unable to change it. It is therefore unlawful for him to attend. If he says, “I will attend but disapprove of it in my heart, and I will not take part with them,”
we say: This is not correct, for if you truly disapproved of it in your heart, you would not remain there. Whatever a person detests in his heart, he cannot remain amidst except under compulsion. Allah, Most High, says:
“Indeed, Allah will gather the hypocrites and the disbelievers all together in Hell.” [al-Nisa’ 4:140]
If someone were to say: “If I do not attend, this will result in severing family ties—for example, if the host is one of his relatives, they have an evil practice, and they invite him; then, if he does not accept, he becomes angry with him and the relationship between them is cut off.”
The answer is: even if this results in severing family ties, for Allah, Most High, says regarding one’s parents—who are among the closest of relatives:
“But if they strive to make you associate with Me that of which you have no knowledge, then do not obey them.” [Luqman 31:15]
Whoever seeks to please people by incurring Allah’s displeasure, Allah will be displeased with him and will cause people to be displeased with him. Thus, this is not lawful. Perhaps his declining to attend a wedding feast