מדרש על שביעית 7:2

10) "shall be (all its produce"): also to serve as fuel for kindling and as an agent for dyeing. We are hereby taught that only what is called "produce" may be eaten (i.e., when it has reached at least one-third of its normal growth) — whence they ruled: When may the fruits of the tree be eaten on shevi'ith? Small figs, if they are red (half-ripe) may be eaten with his bread in the field; if they have ripened, he may take them into his house.