In this verse line a is a statement and line b a simile which illustrates it. The parallelism is in the time of the two events as well as in the events themselves. Come to your grave in line a means to approach death, be near death, ready to die. Ripe old age translates a word whose meaning is uncertain. It occurs also in 30.2, where it is translated by Revised Standard Version as “vigor.” The idea is that Job will die when he is ready, just as a sheaf of grain can only be threshed when it has been made ready (ripe, mature) by the growing cycle. In line b a shock of grain refers to a stack of sheaves, probably wheat.

Comes up to the threshing floor: the word translated comes up suggests a picture of harvest time, when heaps or stacks of sheaves appear to rise up over the fields. Some translators take this to refer to the elevated threshing floor, where the wind would blow the chaff away (Revised Standard Version, New English Bible). Good News Translation compares the ripe grain to life rather than to death: “You will live to a ripe old age.” New Jerusalem Bible implies death by saying “as shocks of grain are taken away in their season…,” and Moffatt “like a sheaf borne home in harvest.” Good News Translation has placed the simile in line a, and in some languages the same will be necessary. In languages where threshing is unknown, it may be necessary to say, for instance, “in the place where the grain is cleaned” or “the place for separating the grain.” If such an expression does not result in a clear picture, it may be better to follow Good News Translation and others which speak of wheat, or “grain that ripens until harvest,” or “until ready to be gathered up.” If grains are largely unknown, a local plant which is gathered when it ripens may be able to be used.

Quoted with permission from Reyburn, Wiliam. A Handbook on Job. (UBS Helps for Translators). New York: UBS, 1992. For this and other handbooks for translators see here .