Is there sin on the husband or wife for the husband refusing to accompany his wife to visit his sister, and what is your advice?

Allah has commanded the upholding of kinship ties. Scholars have differed on defining the kin whose ties must be upheld. However, the husband's sister is not among the kin whose ties must be upheld; rather, she belongs to the general category of kin (kinship through faith) and in-laws, to whom it is desirable to show kindness.

But if the husband prevents his wife from visiting his sister, the wife must obey her husband. The wife can communicate with her husband's sister by phone after seeking her husband's permission to appease her.

The husband must not prevent his wife from upholding ties with his sister without a valid Shar'i reason, as this prevents animosity and disputes.