What is the ruling on taking an additional amount on a loan given by a woman to her neighbor, due to her husband's lack of responsibility, and her desire to invest her money without her husband's knowledge?

A woman lending money to her neighbor in exchange for interest is considered explicit and forbidden usury (riba), based on the Prophet's (PBUH) saying: "Every loan that draws a benefit is usury."

She must return the forbidden interest to its owner. She is only entitled to her principal, as Allah Almighty states: "And if you repent, you may have your principal – [thus] you do not wrong, nor are you wronged."

What is permissible is for the woman to buy goods and sell them for a profit.