I came accross this hadith that is attributed to Ibn Abbas in a tafsir by Ibn Kathir.
[Ibn Abi Hatim recorded that Ibn `Abbas said, "The sun is like flowing water, running in its course in the sky during the day. When it sets, it travels in its course beneath the earth until it rises in the east.'' He said, "The same is true in the case of the moon.'']
I came across an explanation of why the hadith is not considered to be authentic.
https://www.islamweb.net/en/fatwa/336679/ibn-abbaas-statement-about-motion-of-sun
I would like it if someone could better elaborate why the hadith is not considered authentic (even though Ibn Kathir thought the chain of narrators was authentic).