Adding from the profane to the holy - specifically in the realm of time. Specifically, adding to the sabbatical year on both sides, before and after. A biblical verses teaches to cease plowing in advance, and refrain from harvesting afterwards, according to R. Akiva. [What's What: Apparent biblical repetition teaching new details] In this case, Rabbi Akiva and Rabbi Yishmael learn different halakhic details from the same verse. R. Yishmael learns the "extending the holy time into the profane" from the fast of Yom Kippur, which begins a little earlier than the absolute start-time of Yom Kippur. And which is derived from a biblical verse. Also, on the Jubilee year - when slaves go free, and the shofar is sounded... How much is in the hands of the court? Is the shofar what is required? What does this liberty mean? The sages take different approaches, but the real issue is about biblical interpretation, and less because of an underlying difference of approach with regard to the Jubilee itself. Also, the question of what happens in the Diaspora depending on the Jubilee in the Land of Israel.