Two or three Tithes?
Another passage cited in support of three tithes is from the Apocryphal book of Tobit. While not Scriptures, some of these inter-testament books are considered to be relatively good history. The passage in contention is...
Note that the NRSV also footnotes verse 8 as follows... "A third tenth added from other ancient authorities." In the KJV verse eight is a lot sparser...
There was no need for there to be a "third tithe" to account for giving to orphans, widows, etc., as this was an original part of the tithe as proclaimed in the Law. For that matter, each of the elements addressed in this passage from Tobit are all found in the original Law of Moses. Looking after Levites, the poor, widows, aliens, are all part of the original law. With verse 8 (in NRSV) also speaking about eating the tithe in Jerusalem, it again directly refers to what was prescribed by the Law.
What we find interesting in this passage is his perceived separation between a monetary tithe and the other elements. While it was necessary that the firstfruits would be physically carried to Jerusalem and presented to the priests - something that is also shown in this passage - the tithe did not have this requirement. Tobit, the subject of this book (see Tobit 1:1), was from the territory of Naphtali in Galilee. He certainly met the requirements of the Law that his tithe could be converted to money for the purpose of long travel. According to the Law, this money would have then been used to purchase the things necessary for his celebration and for sharing with others (i.e. Deuteronomy 14:24-27). While this apocryphal passage may reflect an actual practice of Tobit, there is nothing in the Law imposing a six year cycle, rather Deuteronomy 14:28 refers only to an every three year cycle for sharing with the Levites, aliens, fatherless and widows in your own town! Perhaps this is why the passage refers to what was taught (as tradition) by his mother, instead of only appealing to the absolute of the Mosaic Law.
As such, this passage is weak evidence for three tithes, and dubious as to whether it reflects even normal practice of the Law. It is certain, by Scriptures and the testimony within the book, that most in the northern kingdom did whatever they pleased, being quite willing to compromise the Law to worship at false altars and images. While Tobit may have, in fact, been trying to follow what he understood of the Law, his knowledge of it was likely compromised as there were no longer Levites teaching it properly in the northern kingdom. At best it would make much of his knowledge of the Law based on family tradition, which may or may not have been completely sound.
Verse 19, above, leaves us with another possible clue to all this as well. At the time of the northern exile (the timeframe of the story of Tobit), Judah began to follow false and compromising practices that had begun in the northern kingdom. It is possible that the way the tithe was being administered in Jerusalem had been, by this time, altered from what God had proscribed in His Law. Even if this was so, it does not change what was originally written and mandated by God.
While the story of Tobit is quite ancient (circa 200 BC), it is certainly a story without authority. Most manuscripts available are Greek translations, though some Hebrew fragments were found at Qumran. Regardless that this account begins in first person, it was certainly not written by Tobit. It was a religious story written well after-the-fact that includes some history. Some of the history within also contradicts details found within other extra-biblical and historical sources. If the story of Tobit had grown in popularity in the final years of Israel (leading up to A.D. 70), as shown by their presence at Qumran, it is quite possible that it became the source for a distorted view of tithing Law - which may have come into practice at this later time. This also may explain why Josephus, who lived during the last years of the temple, referenced a three tithe system. If so, it clearly shows why adopting extra-biblical writings and opinions is dangerous. Over time it becomes very easy for them to be accepted as Scripture, as has happened with the reinstitution of the tithe for the church.