“Abdullah bin Salam (radi Allahu anhu) said: ‘O Allah’s Messenger; the Jews are liars, and if they should come to know that I have embraced Islam, they will accuse me of being a liar.’ In the meantime some Jews came (to the Prophet) and he asked them, ‘What is Abdullah’s status amongst you?’ They replied, ‘He is the best amongst us, and he is our chief and the son of our chief.’ The Prophet (sal Allahu alaihi wa sallam) said, ‘What would you say if Abdullah bin Salam embraced Islam?’ They replied, ‘May Allah protect him from this!’ Then Abdullah came out and said, ‘I testify that La ilaha illAllah (none has the right to be worshipped but Allah) and that Muhammad (sal Allahu alaihi wa sallam) is the Messenger of Allah.’ The Jews then said, ‘Abdullah is the worst of us, and the son of the worst of us,’ and disparaged him. On that Abdullah said, ‘O Allah’s Messenger! This is what I was afraid of.’” [Sahih Bukhari]
When the Prophet (sal Allahu alaihi wa sallam) migrated to Madina there were three Jewish tribes settled there. They had come there a while ago in anticipation of the arrival of the new prophet. Their scriptures described Madina as the place to expect him, and so they had settled there. They had assumed that this prophet would also be of their own lineage, i.e., among the descendents of Ishaq (alaihis salam). Little did they suspect that he would be of the descendents of Ismaeel (alaihis salam).
When the awaited prophet turned out to be an Arab, the jealousy of the Jews knew no bounds. They had looked upon the Arabs as an inferior race and so they refused to acknowledge Muhammad (sal Allahu alaihi wa sallam) as a prophet. They were so intent on maintaining their superiority over the Arabs that they didn’t even hesitate to instantly revoke the status that their most learned rabbi and leader, Abdullah bin Salam, enjoyed amongst them when he acknowledged that the last prophet was an Arab.
Since Abdullah bin Salam (radi Allahu anhu) was well aware of the nature of the Jews, he had foretold what kind of treatment would be meted out to him once he became a Muslim. His courage to stand by the truth, at the cost of losing the prestige and status he enjoyed amongst his people, made him one of the great Sahabah of the Prophet (sal Allahu alaihi wa sallam) and worthy of Allah’s Jannah.