Pesachim 4:2-3

Pesachim 4:2

If a person takes Sabbatical produce from a place where it was gone from the fields (and must be removed from the house) to a place where it was not yet gone from the fields, or vice versa, in either case he must remove it. Rabbi Yehuda says that they tell him to go out and get produce from the field.

Pesachim 4:3

In a place where the accepted practice is to sell small livestock to non-Jews, one may do so. In a place where such is not the accepted practice, one may not do so. It is prohibited everywhere to sell them cattle, calves, and young donkeys, regardless of their physical condition; Rabbi Yehuda permits them to be sold when they are injured. Ben Beseira permits a horse to be sold. [Animals that were typically worked were not sold to non-Jews because they might be worked on Shabbos; an injured animal might not work and a horse would be ridden, which is not a Biblical prohibition.]