Origin of the name of the Jews
7-3-2012 | IslamWeb
Question:
Since when were the Jews named as such when Allaah The Almighty Says (what means): {Ibraaheem (Abraham) was neither Jew nor Christian.} [Quran 3:67]?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger. Yahoodiyyah which is the Arabic equivalent of the word “Judaism,” to which the Jews (Arabic: Yahood) are attributed, came into existence after the time of Ibraaheem (Abraham) and Moosa (Moses), may Allaah exalt their mention. The Jews were called this when both they and Moosa (Moses) said: (what means): {Indeed, we have turned back to You.}[Quran 7:156] "Turned back to you" is in Arabic, "Hudna Ilayk" meaning we repent, so they were called "Yahood", a derivative from "Hudna". ‘Ali The Nasaara (the Sharee‘ah-approved equivalent for the word Christians) were called this due to the saying of 'Eesa (Jesus) Allaah Knows best. 
was reported as stating that the Jews were called this because of their saying, (which means): {Indeed, we have turned back to You.}[Quran 7:156] [At-Tabaraani and Ibn Katheer] Ibn Mas‘ood was also reported to have said that the Jews were attributed to Judaism because of the saying of Moosa 
(which means): {Indeed, we have turned back to You.}[Quran 7:156]: (what means): {Be supporters of Allaah.}[Quran 61:14] [in Arabic the word supporters means Nasaara]. [Ibn Abi Haatim]