For you will not abandon my soul to Sheol,
or let your holy one see corruption [שַׁ֫חַת/šaḥaṯ].
-Psalms 16:10
The word, šaḥaṯ, is most often translated as pit. Why is šaḥaṯ here translated as corruption/decay instead of pit or grave? I understand that this makes the most sense from a New Testament/Septuagint perspective, but how does the Hebrew text lend itself to this particular translation interpretation?
Both! According the Brown-Driver-Brigs Hebrew Lexicon,
While in English these two appear unrelated, both the verb and noun, especially the noun are usually associated with she'ol and thus, digging a pit for a dead body is equivalent to decaying the body and thus associated with corruption.
In the specific case of the noun, it occurs 23 times in the OT and all are associated with the grave/she'ol, eg, Job 9:31, 17:14, 33:18, 22, 24, 28, 30, Ps 7:15, 9:15, 30:9, 35:7, etc. In a few cases it clearly means "corruption/decay" such as, Ps 16:10, 49:9.
The Jewish translators of the Septuagint translated thus:
Ps 16:10 (=Ps 15:10 in LXX) ὅτι οὐκ ἐγκαταλείψεις τὴν ψυχήν μου εἰς ᾅδην, οὐδὲ δώσεις τὸν ὅσιόν σου ἰδεῖν διαφθοράν = because thou wilt not leave my soul in hell, neither wilt thou suffer thine Holy One to see corruption
Ps 49:9 (=Ps 48:10 in LXX) καὶ ζήσεται εἰς τέλος· οὐκ ὄψεται καταφθοράν = and live to the end, [so] that he should not see corruption
Thus, the Jewish translators of the LXX provided a confirmation of the verb meaning in the noun which the English versions have taken as a precedent.
Jewish translations do leave it as "pit":
For Thou wilt not abandon my soul to the nether-world; neither wilt Thou suffer Thy godly one to see the pit.
— JPS Hebrew 1917 / Mechon-Mamre
For You will not abandon me to Sheol, or let Your faithful one see the Pit.
— JPS Hebrew 1985
For You shall not forsake my soul to the grave; You shall not allow Your pious one to see the pit.
— Judaica Press
Almost all English translations use "corruption" or "decay", but that is hardly a recent development.
The Latin Vulgate uses "corruptionem" (4th century CE).
The Septuagint uses "διαφθοράν", which means "corruption" or "destruction" (3rd century BCE).
The NLT perhaps expresses this intent best:
For you will not leave my soul among the dead or allow your holy one to rot in the grave.
Given that the Septuagint was translated by Jews, long before Christianity existed, is it possible that modern Jewish translations are deliberately trying to avoid the Christian implications?
Pit is the most common meaning of שַׁחַת in the MT. Corruption = decay is a possible meaning. The problem with translating it as corruption is it doesn't always mean decay, and thus is a translation that people might interpret incorrectly. שַׁחַת is in a synonymous poetic parallel with Sheol (שְׁאֹול). Thus, a translation should indicate death. This makes grave the best translation. What might make translators lean toward decay is the Septuagint (LXX) translates this word with διαφθορά, meaning decay.
Figure 1. Senses of שַׁחַת in the MT (generated with Logos Bible Software)
