Why is 'Sabbath' often plural in the Greek text (both LXX and NT) yet translated as if it were singular? [closed]

Question

Why is 'Sabbath' often plural in the Greek text (both LXX and NT) yet translated as if it were singular? In my research online, I've been finding that this issue is hotly debated between Seventh Day Adventist scholars, Nestorian scholars, and those belonging to other Christian traditions (due to the former's 'theological stake' in the issue). I am looking for non-doctrinal analysis of the text only (as far as possible). I am aware that an underlying argument is whether or not relevant portions of the New Testament were translated from Aramaic, but for this question I would like to focus solely on the Greek text and other Greek literature that might shed light on this question.

I am also wondering if the use of 'Sabbath' to refer to 'week' is novel to Christian literature, or if it used like this elsewhere (I am aware of the use in the Didache, but this is Christian literature).

The backdrop to this question is these other questions, if you'd like some concrete examples:

• Translation of "first day of the week" in the Peshitta NT
• Translation of "first day of the week" in 1 Corinthians 16:2

Answer 1

This form occurs repeatedly in Mark (1:21; 2:23-24; 3:2; etc), though not to the exclusion of the singular; I have yet to determine the pattern. The lexical helps which I own give only sparse comments on it; The New Linguistic and Exegetical Key to the Greek New Testament (Rogers & Rogers) says at 3:2:

τοῖσ σάββασιν dat. pl. Dat. of time: "on the Sabbath." For the use of pl. for names of festivals s. BD, 78.

BD is there abbreviation for F. Blass and A. Debrunner, A Greek Grammar of the New Testament, which I do not own at the time of this writing and thus that is a dead-end. However, it seems to coincide with what @H3br3wHamm3r81 has said in his answer.

Thayer, in his lexicon, says a bit more, to the same effect:

...plur. τὰ σάββ. (for the singular) of a single sabbath, sabbath-day, (the use of the plur. being occasioned either by the plur. names of festivals, as τὰ ἐγκαίνια, ἄζυμα, γενέσια, or by the Chaldaic form שַׁבָּתָא...

Answer 2

A recent discussion of this whole complex can be found in a lecture on "The Etymology of ‘Sabbath’", which included the following suggestion:

“It seems possible that σάββατα is in fact a borrowing of the Old Aramaic singular noun in the determined state *šabbatā (Middle Aramaic: šabbṯā), which Greek speakers subsequently reinterpreted as a neuter plural and that the singular σάββατον is a back-formation.”