Arabic text
عَنْ عُمَرَ رضي الله عنه قَالَ: قَالَ النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ: «مَنْ لَبِسَ الحَرِيرَ فِي الدُّنْيَا لَمْ يَلْبَسْهُ فِي الآخِرَةِ».
Translation
‘Umar (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) said: "Whoever wears silk in the life of this world will not wear it in the Hereafter."
Explanation
The Prophet (may Allah's peace and blessings be upon him) pointed out that whoever among men wears silk in this world will not wear it in the Hereafter as a punishment for him unless he repents from it.
Source: HadeethEnc.com