כִּֽי־שְׁנ֣וֹת מִסְפָּ֣ר יֶאֱתָ֑יוּ וְאֹ֖רַח לֹא־אָשׁ֣וּב אֶהֱלֹֽךְ׃
因為我那有定數的年歲快要到了，我將走上一條一去不返的路。
Malbim
Eliphaz had argued that the true reward of the righteous is the survival of the soul after death. Job now challenges Eliphaz to bring proof that there is a life after death.
Rashi
will come Will arrive, and then I will go on a way from which I will not return.