What is the opinion regarding the book "Al-Faraj ba'd al-Shiddah" (Relief After Adversity) by Judge Al-Tanukhi?

This book is good in its field, but it does not observe the authenticity of the chain of narration (isnad) or the soundness of the derivation of rulings (istidlal). Therefore, it is not permissible to rely on it in matters of halal and haram and the like.