Answered by Shaykh Hamza Karamali, SunniPath Academy Teacher
Is it permissible or men to wear a tie made of natural silk? What if the tie is not 100% made from natural silk but only parts of it are made of natural silk? Is the prayer valid while wearing it? What is the ruling if one made prayer wearing a tie and did not know it was made of silk?
Wearing a Silk Tie
It is unlawful for a man to wear any garments made of silk. If the garment is made of silk as well as other materials, then if the materials are woven together into a single fabric and the weight of the non-silk component is greater than the weight of the silk component, then it is permissible to wear the garment. However, if the weight of the silk component is greater than the other component, or they are of equal weight, then it is unlawful to wear the garment. If one is unsure of the weight of each component, then, according to Ibn Hajar in the Tuhfa, the default assumption on the garment is that it is permissible to wear.
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[h: I discussed this answer with Shaykh Amjad and he confirmed that based on the details mentioned above, it would not be permissible to wear a tie that is mostly made of natural silk.]
Praying While Wearing a Silk Tie
[h: Although it is unlawful for men to wear silk garments, a past prayer performed wearing silk garments is valid. One is not required to make up the prayer. If, however, one wore such garments knowing that they were made of silk, one is required to repent to Allah Most High and to resolve never to return to the sin again.]
أما إن لم يكن منسوجاً معه بل كان الحريرُ قطعةً مُخاطةً على الثوب غير الحرير فتحل بشرط أن لا يزيد عرض قطعة الحرير على أربعة أصابع وكذا في الطول عند بعضهم، وقال آخرون: لا يتقدر الطول بشيء، ويشترط أيضاً أن لا يزيدَ وزنُ قطعة الحرير على وزن غير الحرير، كما بينه علماؤنا في باب اللباس.