Jamieson, Fausset and Brown on Jeremiah 31:5

5. Samaria--the metropolis of the ten tribes; here equivalent to Israel. The mountainous nature of their country suited the growth of the vine.

eat ... as common--literally, "shall profane," that is, shall put to common use. For the first three years after planting, the vine was "not to be eaten of"; on the fourth year the fruit was to be "holy to praise the Lord withal"; on the fifth year the fruit was to be eaten as common, no longer restricted to holy use (Le 19:23-25; compare De 20:6; 28:30, Margin). Thus the idea here is, "The same persons who plant shall reap the fruits"; it shall no longer be that one shall plant and another reap the fruit.