What is the ruling on taking a loan from an Islamic bank to pay off a sister's debt, which might lead to her imprisonment, knowing that she lost the amount she borrowed for trade?

Helping people, fulfilling their needs, and alleviating their distress are among the greatest acts of righteousness and goodness, especially if it is for a relative. Assisting your sister in paying off her debt is an act of righteousness for which Allah will reward you immensely. It is essential to ensure that the transaction with the Islamic bank is permissible, and you can refer to the Sharia supervisory boards of banks for inquiries.