Jas 4:15

“James is not trying to take away our freedom to decide, but he is showing us that it is not just what we want that matters. We need God's grace to complement our efforts and ought to rely not on them but on God's love for us. As it says in Proverbs: "Do not boast about tomorrow, for you do not know what a day may bring forth."”

“Having interrupted the discourse midway with this comparison, he returns to it again and continues. Here is the connection: "Come now, you who say, 'Today or tomorrow we will go to such and such a city, spend a year there, and buy and sell and make a profit'" (Jas. 4:13)... "Instead you ought to say, 'If the Lord wills, we shall live and do this or that'" (Jas. 4:15). Having interrupted the connection of the discourse with the example by which the apostle wished to show more strikingly the vanity of worldly cares proceeding from pride, he then adds what was omitted. The course of the speech is this: "You, in your arrogance, boast." Who? "You who do not know what will happen tomorrow, for what is your life..." and so forth. With the words "what is your life?" he prepared for himself the way to this subtle precept; then he adds the instruction itself, doing so most appropriately.”

“For what is your life? it is a vapour. We frequently meet with three beautiful comparisons in holy writ. “Remember that my life is but wind….As a cloud is consumed, and passeth away; so he that shall go down to hell, shall not come up.” (Job vii. 7, 9.) “Man is like to vanity, his days pass away like a shadow.” (Psalm cxliii. 4.) Similar expressions also frequently occur in profane authors. Nemo tam Divos habuit faventes Crastinum ut possit sibi polliceri. (Seneca) With reason then did our Saviour say, “Be you then also ready, for at what hour you think not, the Son of Man will come.” (Luke xii. 40.) (Calmet)”

“for that you should say, If the Lord wills, and if we live, we will do this or that. But now you glory in your arrogance. All such rejoicing is wicked. Furthermore, having intercepted such speech by this example, it again returns from the perspective to what was following. For the whole particle is to be ordered in this way: Now you who say, "Today or tomorrow we will go to that city, and we will spend a year there, and we will trade and make a profit," for what you ought to say. If the Lord wills, and if we live, we will do this or that. "But now you glory in your arrogance." Since this was truly a consequence of the discourse, it does not do this, but after it interrupts the continuity of the discourse with an example, it subsequently adds what it intended, by portraying the thing and proving the vanity that lies beneath what distracts us regarding this world. It is to be understood in this way: "Glory in your arrogance." Who are you that do not know what will happen the next day? What is your life? etc. By saying, "What is your life?" it despises life, and by this, it paves the way with an example set against brittleness, thus it also adds an example, rendering this most solid. "Glory in your arrogance." The arrogant and arrogance are affections for non-sustaining things. Therefore, it is also called ἁλαζών, which means "living with the sea," that is, living with something unstable and lacking permanence. "All such rejoicing is wicked." James repeats the empty boasting that desires to arise from pride, and as if concluding his speech, he supposes that it is evil: if it is evil, it is certainly also from the Evil One. However, those who have been consecrated to the Lord through baptism should not receive any corruptions from the Evil One.”