I have heard that the restoration of the state of Israel is a fulfillment of one or more Biblical prophecies. But I cannot find any explicit reference to it.
Is this really a fulfillment of prophecy, if so which one(s)?
As seen in the Old Testament books, God repeatedly judges Israel, and temporarily removes His people from the land, but when they repent, He keeps that original promise and restores them to their land. It was still their land in God's mind, they were simply temporarily removed from it.
Unless God lied, or was mistaken in verse 15 above, the land is promised to them forever.
Israel's restoration is implied in perpetuity via the promise above. No further revelation is needed
Your question can be answered in two ways:
In a matter like this one I think the 2nd option clearly is the best one. I would build my case along these lines:
It would be impossible to provide all details of how my thinking has evolved on this issue, but the end result is that I view present day Israel as the probable fulfillment of biblical prophecies in an embryonic form. I do not think that such belief warrants political support for repressing the Arab population, e.g. as in advocating forced transfer from the west Bank. Ethics must be a consideration, as well as eschatology.
However, if events occurred that would prove today's nation of Israel as just another Maccabean-like era, my faith in God would not be severely shaken, although any such event would surely be the result of a disastrous war or collapse, that would probably ensure a 2nd holocaust. Thus, it should be avoided, anyway, for simple ethical reasons. That means I support the basic tenant of Zionism - that it is a good idea for the Jewish people to have a national home in their ancient homeland - even if its present day manifestation is not necessarily the product of biblical prophecies.
In Ezekiel 36, the prophet has a vision of a valley of "dry bones." When asked if these bones could yet live, Ezekiel wisely says, "You alone know, O Lord." After this, the Lord miraculously makes the bones come together and come alive.
It is explicitly stated that this refers to Israel. Ezekiel, speaking for the Lord says:
Hal Lindsey, (The Late Great Planet Earth), for instance, explains how he sees this as the restoration of Israel in this video Note: Hal Lindsey is a controversial figure, to say the least, but he is the direct inspiration for many premilennial dispensationalists, such as Tim LaHaye (Left Behind), John Walverood, Ed Whisenant, and others.
Ed Whisenant's well-known work 88 Reasons why the Rapture will occur in 1988 was fundamentally based on the conflation of this event, Jesus' parable of the fig tree (not a generation shall pass away until these things occur) and the restoration of Israel in 1948.