Is a widow required to wear only white clothes during her ‘iddah (post-marriage waiting period), or she is allowed to wear clothes with other colors?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

A widow who is observing her ‘Iddah is not required to wear white clothes. Rather, she is allowed to wear whatever clothes she wants, as long as it is not an adornment. In his explanation of Saheeh Muslim, An-Nawawi said, "All scholars regarded it allowed for a widow to wear white clothes during her ‘Iddah, but some of the late Maliki scholars forbade the nice white clothes used for adornment."

Yet, what is forbidden is the clothes that are used for adornment. The following is stated in Al-Mawsoo‘ah Al-Fiqhiyyah: "She (a widow during ‘Iddah) is allowed to wear a garment that is not dyed with a scented dye, even if it is precious. She is allowed to wear all types of clothes, regardless of the color, as long as it is not considered adornment by custom."

In Al-Mughni, Ibn Qudamah said:

The second section: adornment by clothes. She (a widow during ‘Iddah) is forbidden to wear clothes that are dyed for beautification purposes, such as those dyed with safflower extract and other reddish color-dyed clothes as well as other clothes whose color is a beautifying factor (of the clothes), such as pure blue, green and yellow-dyed clothes. It is impermissible for a widow in her ‘Iddah to wear such clothes. The Prophet, sallallaahu ‘alayhi wa sallam, said, "She is forbidden to wear a dyed garment." He also said, "She is not allowed to wear clothes dyed with safflower or russet-dyed clothes."

However, she is permitted to wear clothes whose color is not intended as a beautifying factor, such as dark blue, black and dark green-dyed clothes because they are not considered adornment.

Allah knows best.