He replied:
Praise be to Allah. It is not permissible to sew silk garments for someone who will wear them in a forbidden manner, such as a man wearing pure silk outside warfare and for no medicinal purpose, for this constitutes cooperation in sin and transgression. The same applies to making gold and silver vessels, according to the sounder of the two views held among the majority of scholars. It likewise applies to making instruments of amusement, images of living beings, idols, crosses, and similar things fashioned in a form in which their use is forbidden. The same applies to making wine. As for places of sin, unbelief, and the like, payment received for such unlawful work is illicit, and such conduct must be denounced.
However, sewing silk garments for someone who will wear them lawfully is permissible. This includes sewing them for women, even though the man touches the silk while sewing, since this is not forbidden. The same applies to crafting gold and silver items for someone who will use them lawfully.
It is permissible to use silk thread in men’s clothing. Decorative bands, edging, and similar features are likewise permissible within the allowance established by the Sunnah: an area two, three, or four fingers wide. The Prophet, peace and blessings be upon him, had a robe edged with silk.