Albert Barnes Commentary Job 14:5

"Seeing his days are determined, The number of his months is with thee, And thou hast appointed his bounds that he cannot pass;" — Job 14:5 (ASV)

Seeing his days - are “determined,” since man is so frail and so short-lived, let him alone, that he may pass his little time with some degree of comfort and then die. See the notes at (Job 7:19–21). The word “determined” here means “fixed, settled.” God has fixed the number of his days, so that they cannot be exceeded. Compare the notes at (Isaiah 10:23), and notes at (Psalms 90:10).

The number of his months are with you - You have the ordering of them, or they are determined by you.

You have appointed his bounds - You have fixed a limit, or have determined the time which he is to live, and he cannot go beyond it. There is no elixir of life that can prolong our days beyond that period. Soon we will come to that outer limit of life, and then we must die.

When that is, we do not know, and it is not desirable to know. It is better that it should be concealed. If we knew that it was near, it would fill us with gloom and deter us from the efforts and the plans of life altogether. If it were remote, we would be careless and secure, and would think there was time enough yet to prepare to die.

As it is, we know that the period is not very far distant; we do not know but that it may be very near at hand, and we should always be ready.