Is it a sin or a transgression to refuse to host one's brother's children due to the wife's inability to care for them, especially with the ongoing estrangement between the two brothers?

Maintaining kinship ties is obligatory, and severing them is among the major sins. To foster love among siblings, giving gifts is recommended, as it helps remove grudges. One can also seek the help of a mediator for reconciliation. However, refusing to host one's nephews due to an inability to care for them is not a sin, according to Islamic law.