Babylonian Talmud, and younger than three if they're marrying a Cohen.
Some quotes from the Babylonian Talmud on the re-growth of infant girl's hymens:
"He was gone, leaving Winston holding the scrap of paper, which this time there was no need to conceal. Nevertheless he carefully memorized what was written on it, and some hours later dropped it into the memory hole along with a mass of other papers." - 1984 by George Orwell, chapter 14