reliable sources

Q: Can I wwear a sherwani which has brocade work on it? (Brocade is a class of richly decorative shuttle-woven fabrics, often made in colored silks and with or without gold and silver threads).

I already purchased it and its hard to return. I asked the worker if it contains silk, he told me that it doesn't contain silk. Can I wear it on my nikaah? 

Q: What are the sources in deen which can be relied upon? If something was done by a righteous scholar which is not proved by sunnah or Sahaabah or fiqh, will it be part of deen?