Leviticus 25:10

The fiftieth year. Opinion has long differed as to whether the jubilee was the year following the sabbatical 49th, resulting in two successive cropless years, or whether the 50th year, counted inclusively, was the same as the 49th. One prevailing Jewish opinion is that the former was true under the first temple, and the latter afterwards. Verses 8-11 and the analogy of the Pentecost reckoning (ch. 23:15, 16), seem to imply a separate jubilee year, but vs. 20-22 are ambiguous. The only sabbatical years mentioned in history are after the exile, and they are not referred to as jubilees.

We have no historical proof of how, or whether, Israel followed these instructions before the captivity. There is little doubt that after the captivity the Jews observed at least the seventh year and that God did bless them. The best evidence of this observance is the fact that Alexander the Great, and later Julius Caesar, exempted the Jews from paying taxes in sabbatical years, on the ground that they would have no income that year (Josephus Antiquities xi. 8. 6; xiv. 10. 6).