There are lots of differences in the changes and varieties of Hebrew between different groups like the Ashkenazim, Sephardim, Chasidim, Teimanim and so on. Those differences hinge upon the same sort of regional dialect differences that might show up as in speakers of English between New York or London. In the case of Gefen or Gafen in the bracha “…borei pri haG-fen” said before brinking wine or grape juice, there is something else at play on a more philosophical level.
Unlike other other differences in accent between Jewish groups—whether one says “Shabbat” or “Shabbos” for instance—is down to the differences in any other accent wherein certain sounds are articulated variably, in this case the Ashkenazim and Sephardim would normally both say the word in the same way: “gefen”. This is not the only example either where brachas (blessings) are said differently like this either.
Pausal Form
Basically, Biblical Hebrew has a feature whereby if a word has the vowel pattern (-e-e-) at the end of any type of clause, there vowels change to (-o-e-). For instance, in Exodus 21:
וְאִם־אָס֖וֹן יִהְיֶ֑ה וְנָתַתָּ֥ה נֶ֖פֶשׁ תַּ֥חַת נָֽפֶשׁ׃ (v’im ason, yihi’e vnatatah nefesh tachat nafash)
Note that in general, the transliterations follow Modern Israeli Hebrew style
But if damage happens, the penalty will be life for life,
עַ֚יִן תַּ֣חַת עַיִן שֵׁ֖ן תַּ֣חַת שֵׁ֑ן יָ֚ד תַּ֣חַת יָד רֶ֖גֶל תַּ֥חַת רָֽגֶל׃ (ayin tachat ayin, …regel tachat ragel)
eye for eye, tooth for tooth, hand for hand, foot for foot,
כְּוִיָּה תַּ֣חַת כְּוִיָּה פֶּ֖צַע תַּ֣חַת פָּ֑צַע חַבּוּרָה תַּ֖חַת חַבּוּרָֽה׃ (kviah tachat kviah, petzah tachat patzah…)
burn for burn, wound for wound, bruise for bruise.
So everyone would say “gefen” or any other word like this in a normal context, but the pausal form changes the vowels of the word.
There are two points of contention about whether it should be used for blessings though. First is that Sephardim and some others argue that the “amen” that follows a bracha is part of the sentence and therefore the word in question isn’t at the end, and secondly that brachas are in Mishnaic Hebrew, but the pausal form only exists in the Tanakh in Biblical Hebrew. Either one of these points would point to the word being “gefen” but that is not how those other than Sephardim argue on the matter.
It is very important to follow one’s customs on these matters. Without a Sanhedrin as a body to settle disputes, using one’s local customs and variety. It is always best to say what one’s family has said as a matter of honoring them, and to not suggest what they have done going back generations and generations is wrong. If one doesn’t have strong customs, speak to a Rabbi or look back to the last generation who did have strong local customs.
Sources:
- Herzog, George. “The Main Differences between Sephardic and Ashkenazi Pronunciation.” The Jewish Quarterly Review 29.1 (1938): 69-91.
- Saenz-Badillos, Angel. A History of the Hebrew Language. Cambridge University Press, 1993.
- Goldstein, David. “Some Aspects of Sephardic Phonology.” Language 44.2 (1968): 364-371.
- Damesek, Daniel. “Phonological Variation in Ashkenazi and Sephardi Hebrew.” Proceedings of the Annual Meetings on Phonology 1 (2016).
- Schiffman, Lawrence. “Hebrew in the Context of Language.” AJS Review 17.2 (1992): 163-170.