Shaykh Ibn `Uthaymeen
al-Muqarrab li-Ahkaam al-Janaa.iz – Question 142, Page 122
Question: Is it permissible to wear black clothing when mourning the deceased, particularly if he (the deceased) is the husband?
Response: The wearing of black (clothing) at times of tragedy is a false custom, and one which has no basis (in Islaam). At times of tragedy, it is befitting for a person to do that which has been legislated (for such times); So he should say:
«To Allaah we belong and unto Him is our return. O Allaah, recompense me for my affliction and replace it for me with something better.», transmitted by Muslim, No.1525
And if he were to say it with firm belief and content (with what Allaah has decreed), then certainly Allaah (Subhaanahu wa Ta`aala) will reward him for that and compensate him with that which is better.
As for wearing specific clothing, such as black or that which is similar, then indeed there is no basis for this (in Islaam); It is falsehood and detested.
WEARING LONG GARMENTS OUT OF PRIDE
Narrated Abu Hurairah (RA): The Prophet (SAW) said, “The part of an Izar which hangs below the ankles is in the Fire.” (i.e. the one who wears the Izar [lower-half body cover) that hangs below the ankles (with conceit) will be in the fire of Hell]. (See Fath Al-Bari, Vol. 12, Page 370) [Sahih Al-Bukhari 7:678-O.B.]
Narrated Ibn Umar (RU): Allah’s Messenger (SAW) said, “Whoever allows his lower garment to drag out of vanity will find that Allah will not look at him on the Day of Resurrection.” On this Abu Bakr (RA) submitted: “O Allah’s Messenger! My loincloth keeps sliding down though I take care to pull it and wrap it.” Allah’s Messenger (SAW) said, “You are not of those who do it out of vanity.” (Sahih Al-Bukhari)
Allah’s Messenger (SAW) has given a severe warning to those who intentionally wear a dress which is dragging along the ground because this is a sign of arrogance. Yet, if a person’s garment unintentionally slips downward he will not be put to accountability. (Riyad-us-Saliheen English Translation Volume One Page 669)
Narrated Abu Hurairah (RA): Allah’s Messenger (SAW) said, “On the Day of Resurrection, Allah will not look at him who trails his lower garment out of pride.” (Sahih Al-Bukhari and Muslim)
A disregard of Allah’s Favors and gifts means ungratefulness which is essentially manifested in a haughty attitude. It is also a sign of arrogance that one wears a dress with the hem trailing on the ground. (Riyad-us-Saliheen English Translation Volume One Page 669)
Narrated Abu Hurairah (RA): Allah’s Messenger (SAW) said, “What is below the ankles of a lower garment is condemned to the Fire (Hell).” (Al-Bukhari)
The apparent sense of the Hadith words is that the part of the dress hanging down below the ankles will be put into Hell-fire. Yet, if this is the fate of the particular piece of cloth the wearer will surely go to Hell. When Nafi (RA) was asked about it he said, “Yes, but what sins have the clothes committed?” (Riyad-us-Saliheen English Translation Volume One Page 669)
Narrated Abu Dharr (RA): I heard Allah’s Messenger (SAW) saying, “There are three to whom Allah will neither speak on the Day of Resurrection nor will he look at them nor purify them (i.e., of their sins), and they will be severly tormented.” When he repeated this (statement) thrice, Abu Dharr (RA) said: “They are doomed and destroyed! (But) who are they, O Allah’s Messenger (SAW)?” He said, “One whose lower garment trails, one who boasts of kindness shown to another; and one who promotes sale of his business by taking false oaths.” (Sahih Muslim)
This Hadith sheds light on three major sins which, unfortunately, prevail in Muslim societies. May Allah amend the lapses of Muslims behavior! (Ameen) (Riyad-us-Saliheen English Translation Volume One Page 669)
There are many, many more ahadith about the prohibition of wearing long garments out of pride.