Faðir, fyrgefðu þeim, þvíat þeir vitu eigi hvat þeir gera.
From a fragment of a 12th century translation belonging to the Arnamagnaean manuscript collection, quoted by 19th century historian and philologist Carl Richard Unger, appearing in an 1899 collection of Old Norse fragments put together in one PDF in recent years. It was written in Norway, presumably eastern, according to the 1899 collector. It's the only verse from chapter 23 in the collection, so I was happy to find it.
Actually: vitun doesn't mean anything in (at least: standard) old-norse; vitund or vitand would be "knowledge" and "to know" would be vita (vitu "they know") - as you correctly posted above; i think MiclePlaton didn't make a typo but refered to AndrijAndrusiak's original post.
Kvan skal synge meg, i daudsvevna slynge meg, når eg på Helvegen går, og dei spora eg tror er kalde, så kalde. Beautiful. One of the best spiritual songs for those who wish to celebrate the old ways. No joke, I'm actually listening to that album right now and the song just came on.
In this sentence 'for' means 'because'. The entire passage is what Jesus spoke on the cross about his tormentors right before he died--something like "forgive them for they know not what they do." Prayers and other old religious texts often retain older language forms, while the everyday language has dropped them.
Eli, Eli, Lama Sabachthani, or Eloi, as in other scrptures; the beauty of it being that each apostle wrote independently from each other and provided their own living experiences, so the difference between Eli and Eloi, but converging to the same Jesus, or Jeshua, as well. I understood very well what DUO wrote, and it was helpful in the sense that it showcased a very well-known and recognizable sentence, as in " Forgive them, Father, for they do not know what they are doing."
It is not an exception, and I did not hear 'vyeh' in the recorded sentence. There are some significant variations in how things are pronounced in Norway, and it's possible that a dialectic version has a very long 'e' and/or dropped 't' that could sound kind of like you suggest. But I have never heard it said that way.
This would probably be less confusing to people not associated with the phrase if you directly translated it, since the original poetic text in English, "For they know not what they do," does apparently, translate directly into the Norwegian...the older poetic English style would also maybe tip people off to the fact that it's a reference to something in literature...maybe....?