Of the Words Which Were Spoken Out of the Ship on the Subject of the Sower, Whose Seed, as He Sowed It, Fell Partly on the Wayside, Etc.; And Concerning the Man Who Had Tares Sowed Over and Above His Wheat; And Concerning the Grain of Mustard Seed and the Leaven; As Also of What He Said in the House Regarding the Treasure Hid in the Field, and the Pearl, and the Net Cast into the Sea, and the Man that Brings Out of His Treasure Things New and Old; And of the Method in Which Matthew's Harmony with Mark and Luke is Proved Both with Respect to the Things Which They Have Reported in Common with Him, and in the Matter of the Order of Narration
88 Matthew continues thus: “In that day went Jesus out of the house, and sat by the seaside: and great multitudes were gathered together unto Him, so that He went into a ship and sat, and the whole multitude stood on the shore. And He spoke many things unto them in parables, saying;” and so on, down to the words, “Therefore every scribe which is instructed in the kingdom of heaven is like a man that is an householder, which brings forth out of his treasure things new and old.” That the things narrated in this passage took place immediately after the incident touching the mother and the brethren of the Lord, and that Matthew has also retained that historical order in his version of these events, is indicated by the circumstance that, in passing from the one subject to the other, he has expressed the connection by this mode of speech: “In that day went Jesus out of the house, and sat by the sea-side; and great multitudes were gathered together unto Him.”
For by adopting this phrase, “in that day” (unless perchance the word “day,” in accordance with a use and wont of the Scriptures, may signify simply “time”), he intimates clearly enough either that the thing now related took place in immediate succession on what precedes, or that much at least could not have intervened. This inference is confirmed by the fact that Mark keeps by the same order. Luke, on the other hand, after his account of what happened with the mother and the brethren of the Lord, passes to a different subject.
But at the same time, in making that transition, he does not institute any such connection as bears the appearance of a want of consistency with this order. Consequently, in all those passages in which Mark and Luke have reported in common with Matthew the words which were spoken by the Lord, there is no questioning their harmony with one another. Moreover, the sections which are given by Matthew only are even much more beyond the range of controversy. And in the matter of the order of narration, although it is presented somewhat differently by the various evangelists, according as they have proceeded severally along the line of historical succession, or along that of the succession of recollection, I see as little reason for alleging any discrepancy of statement or any contradiction between any of the writers.
Source: The Harmony of the Gospels (New Advent)