Is it obligatory for a woman whose husband has passed away to wear only white during her iddah, or is it permissible for her to wear other colors?

A woman observing 'iddah (waiting period) due to the death of her husband is not obligated to wear white. Rather, she is permitted to wear any clothes she wishes, as long as they are not garments of adornment. This includes clothes dyed for beautification, such as those colored with 'usfur (safflower) or saffron, and any brightly colored garment intended for adornment. However, if the dyeing is not intended for adornment, such as navy blue, black, or dark green, then it is not prohibited.