As'salamu Alaikum dear brother Sama,
Here is a much stronger evidence from the Jewish Rabbis and Jewish sources, and even the Bible itself:
1- The believers' title was always Muslims. Salamays, Mushlams, Mushlemanies, etc... This is also where we get
Shalom from. It is SALAM. The Jews' deficient tongue pronouces the S as SH and the soft A as O.
2- Moses' in-laws in the Bible were Salamys. You can think of them as Arabia's Muwahiddeen (monotheists) before Prophet Muhammad became a Prophet.
3- Allah Almighty called Islam SILM in the Glorious Quran. Because indeed, the religion before Allah Almighty is Islam, as He said, and before Prophet Muhammad it was called also Silm.
4- Jesus also in the Bible called the believer's title Mushlem.
Peace be upon all of the Prophets of Allah Almighty.
Please visit:
www.answering-christianity.com/ac.htm#capsuleTake care,
Osama Abdallah