Exodus 23:10 Midrash

וְשֵׁ֥שׁ שָׁנִ֖ים תִּזְרַ֣ע אֶת־אַרְצֶ֑ךָ וְאָסַפְתָּ֖ אֶת־תְּבוּאָתָֽהּ׃

And six years thou shalt sow thy land, and gather in the increase thereof;