I believe the following fatwa is important because a lot Salafis tend to be very lenient in narrating and sharing narrations from the Salaf, unsure if they are authentic or not. Shaikh Muqbil rahimahullah clarifies here that an athar, like a Hadith, must be authentic and be supported by the Quran and Sunnah.
Something to be keen upon.
Can an Athar Contain What a Hadith Cannot [i.e of Weakness]?
No, it is necessary for it to be established. An athar leads to things and our Scholars have not ceased to speak about some narrations that they have routes that are weak. Allahu Mustaan. Whoever claims a separation [between a Hadith and Narration] then upon him is the proof.
That is, that which is established only is taken?
We take the origin of that which is established. Like a verse of the Quran, we take it. Or a Prophetic Hadith, we take it and that is sufficient.
.أَوَلَمْ يَكْفِهِمْ أَنَّا أَنْزَلْنَا عَلَيْكَ الْكِتَابَ يُتْلَىٰ عَلَيْهِمْ
Is it not sufficient for them that We have sent down to you the Book (the Quran) which is recited to them?
Is it not sufficient?
Yes, it is. However, if it confirms?
If the chain is established and it explains a verse or Hadith, then we seek aid in the understanding of our Salaf rahimahullah. As for if they speak from themselves and there is not a verse or Hadith, then we do not blind follow them in this affair. Also, if they are Isra’iliaat stories, then they are not learned except by revelation from the Book and the Sunnah. If the chain is like the sun [in clarity] we hold back regarding it. Likewise in the conditions of Paradise, Hell, and trials/tribulations. What is important is that we do not have except the Book of Allah and the Sunnah of the Messenger sallahu alayhi wa salam and they are sufficient”.
Faisal Ibn Abdul Qaadir Ibn Hassan