Matthew 1:17

“So all the generations from Abraham, etc.] The Evangelist having traced the genealogy of Christ from Abraham, which he divides into “three” parts, because of the threefold state of the Jews, “first” under Patriarchs, Prophets, and Judges, “next” under Kings, and “then” under Princes and Priests, gives the sum of each part under its distinct head; “so all the generations”, that is, the degrees of generation, or the persons generated from Abraham to David, both being included, “are fourteen generations”; as there were, and no more, and are as follow, Abraham, Isaac, Jacob, Judah, Phares, Esrom, Aram, Amminadab, Naasson, Salmon, Boaz, Obed, Jesse, David. And from David until the carrying away…”

“So all the generations from Abraham to David are fourteen generations; and from David until the carrying away--or migration. into Babylon are fourteen generations; and from the carrying away into Babylon--the migration of Babylon. unto Christ are fourteen generations--that is, the whole may be conveniently divided into three fourteens, each embracing one marked era, and each ending with a notable event, in the Israelitish annals. Such artificial aids to memory were familiar to the Jews, and much larger gaps than those here are found in some of the Old Testament genealogies. In Ezr 7:1-5 no fewer than six generations of the priesthood are omitted, as will appear by comparing it with Ch1…”

“So all the generations ... - This division of the names in the genealogical tables was doubtless adopted for the purpose of aiding the memory. It was common among the Jews; and other similar instances are preserved. The Jews were destitute of books besides the Old Testament, and they had but few copies of that among them, and those chiefly in their synagogues. They would therefore naturally devise plans to keep up the remembrance of the principal facts in their history. One method of doing this was to divide the tables of genealogy into portions of equal length, to be committed to memory. This greatly facilitated the remembrance of the names. A man who wished to commit to memory the names of…”

“So all the generations - Observe, in order to complete the three fourteens, David ends the first fourteen, and begins the second (which reaches to the captivity) and Jesus ends the third fourteen. When we survey such a series of generations, it is a natural and obvious reflection, how like the leaves of a tree one passeth away, and another cometh! Yet the earth still abideth. And with it the goodness of the Lord which runs from generation to generation, the common hope of parents and children. Of those who formerly lived upon earth, and perhaps made the most conspicuous figure, how many are there whose names are perished with them? How many, of whom only the names are remaining? Thus are we…”

“1:17 Matthew states that each period has fourteen generations, but the first and third periods list only thirteen. A legitimate Jewish and Old Testament approach would count David in both the first and second groupings and include Jesus in the third grouping. This suggests that Matthew is probably stressing the gematria (letters representing numbers): The letters in the Hebrew word dawid (“David”) also add up to fourteen. Matthew is highlighting Jesus’ credentials as the Messiah (1:1).”