If you pray wearing silk or gold

That which is cut off from the jild [flesh, meat] of those animals whose flesh is permissible to eat and those animals whose flesh is impermissible to eat is considered dead. It does not become pure except by tanning.

In addition, I forbid men from wearing silk.

He who wears silk and prays in it, he does not have to repeat the prayer.

This is because silk is not impure. Not wearing it is a form of worship. You do not wear it because it is impure but because it is a form of worship not to wear it [since men have been told not to wear it and when you obey a command of Allaah it is worship]. And because its price [in sale and trade] is permissible.

Indeed, women wear it and pray in it.

Likewise, I forbid men from wearing gold rings and other gold items. If they wear them and pray in them, then they have done evil and have been disobedient if they know of the prohibition of wearing gold items, but they do not have to repeat the prayer. This is because gold items are not impure. Do you not see that those things which are considered impure are considered impure for both men and women and women pray while wearing gold items?

al-'umm by al-Shaafi'i
Volume 1 Page 111