In the bible the word is Sabbath, and several hebrew words have the dental fricative.
But modern Jews (that is, the movie ‘Holy Rollers’) seem to pronounce it 'Shahbus" and don’t use any th.
Did the ‘th’ sound disappear? Is it gone from Arabic as well?
“Shabus” (or “Shabes”) is an Ashkenazi pronunciation of the word. In general, with Ashkenazi dialect of Hebrew, the letter “Taf” (ת) in Hebrew at the end of words is pronounced “s” (as in “Shabbes”, “chaloimes”, and “tzitzes”). Sephardi pronunciation, which is what is adopted in Israel, pronounces Taf as “t” - “Shabbat”, “chalomot” and “tzitzit”. With some “Mizrahi” versions of Hebrew, I think, they pronounce Taf more like the English unvoiced “th”. I think I heard some old Iraqi and Yemeni Jews pronounce it like that.
According to wikipedia (had to get that in), “SHAH-bus” is the Ashkenazi pronunciation. I have often heard it pronounced “shah-BOT”
There are several “Ashkenazi pronunciations”. I believe they are Lithuanian, Galician and Ukrainian (though the Ukrainian and Galician are pretty close).
The thing is that Yiddish is a high Germanic tongue (English, Dutch and Plattdeutsch are low) and in the high Germanic dialects the change t --> s or ts (e.g. Fut --> Fuss, or Teit --> Zeit) happened in certain contexts (along with p --> f or pf (e.g. Pfeffer) and, in some dialects k --> ch or kch) and this happened too, to the Hebrew spoken by Yiddish speakers. I am told that something similar happened to English speakers of Latin when the former underwent its big vowel shift.
The word in the bible is “Sabbath” in the English translations. In the Hebrew text, it was always Sh-B-T (or Sh-B-S, there was variation in pronuncation of the final letter taf, as mentioned by Terr. And, of course, there are no vowels in the original text.
While we’re at it, all those J-names in the bible: Joseph, Jacob, Jeremiah, Joshua, Jesus. There was no letter “J” in ancient Hebrew, those were all Y’s. The German translators of the bible used J, since the letter J in German is pronounced “y.” The English translators just took the names straight over from the German translation, and pronounced the first letter as J. Thus Joseph is (in original text) really Yosef, etc.
New Testament names would have been written in Greek.