Assalamualaikum, if a hadith is not in the top authentic hadith books e.g Bukhari, Muslim, Tirmidhi etc and instead says something like Sahih Ibn Khuzaymah should you feel comfortable in being especially doubtful of it?
Alaikumassalam wa rahmatullah,
Each scholar had their own way of verifying hadiths. Just because it is not in Sahih al-Bukhari and Muslim it does not mean the hadith is lower in quality. What many Muslims don’t know is that Sahih al-Bukhari and Muslim are not meant to be encyclopedias of hadith. They are handbooks for legal scholars, making it easy to quickly look up hadiths on questions like fasting or Hajj. They intentionally did not include many high-quality hadiths that were not relevant to their aims. A book like Sahih Ibn Hibban is perhaps as good as al-Bukhari. Also note that Sahih al-Bukhari contains many low-quality hadiths that were criticized by other scholars, and Sahih Muslim is perhaps five times as bad when it comes to including low-quality hadiths, because Imam al-Bukhari had higher standards and was more knowledgeable about the reliability of hadith transmitters.
Note that some collections intentionally include many weak hadiths, such as the Musnad of Imam Ahmad and al-Tirmidhi’s collection. If the collection’s title does not have the word “Sahih” in it then it is likely to contain weak hadiths too, because the scholars’ intention was simply to collect as many hadiths as they could for research purposes regardless of their authenticity.
Personally I do not differentiate at all between different hadith collections, I combine chains from all the collections in my studies, determining the hadith’s authenticity by looking up the reliability of each transmitter.