What is the ruling of Islamic law concerning a husband whose sisters continue to boycott his wife and refuse reconciliation with her, and he buys his children's clothes from his sisters against his wife's wishes, under the pretext that they are cheaper, and he refuses to give her money to choose Eid clothes? And is he sinful for that?

It is impermissible for a Muslim to abandon his brother for more than three nights, and the sin of abandonment falls upon the one who abandons. There is no harm for the husband in buying clothes for his children from his sister; rather, it is recommended if it strengthens kinship ties, and he has the freedom to choose in that regard. The husband is advised to treat his wife gently and to address the matter with wisdom, and the wife is advised to assist her husband in maintaining his kinship ties.