That the Messenger of Allah (ﷺ) said: "Indeed when a Jew gives Salam to one of you, then he is only saying: 'As-Samu 'Alaikum' (Death be upon you) so say: "Alaik (And upon you).'"

This Hadith is Hasan Sahih.
Jami` at-Tirmidhi Book 21, Hadith 66
← Previous Hadith That the Messenger of Allah (ﷺ) said: "Do not precede the Jews and the Christians with the Salam. And if one you meets one of them in the path, then force him to its narrow portion."

There are narrations on this topic from Ibn 'Umar, Anas, and Abu Basrah Al-Ghifari the Companion of the Prophet (ﷺ).

This Hadith is Hasan Sahih. And regarding the meaning of this Hadith: "Do not precede the Jews and the Christians": Some of the poeple of knowledge said that it only means that it is disliked because it would be honoring them, and the Muslims were ordered to humiliate them. For this reason, when one of them is met on the path, then the path is not yielded for him, because doing so would amount to honoring them.

Jami` at-Tirmidhi Book 21, Hadith 65 Next Hadith → From Jarir bin 'Abdullah that the Messenger of Allah (ﷺ) sent a military expedition to Khath'am. So some people (living there) sought safety by prostrating, but they were met quickly and killed. News of this reached the Prophet (ﷺ) upon which he commanded that they be given half of the 'Aql (blood money). And he said: "I am free from every Muslim that lives among the idolaters." They said:"O Messenger of Allah: How is that ?" He said: "They should not see each other's campfires."

Jami` at-Tirmidhi Book 21, Hadith 67