Parallel passage: Luke 6:47-49 (cf. also Ezekiel 13:10-16). A solemn close to the sermon. By the similitude of two builders our Lord warns his followers that to have heard his words will have been useless unless they put them into practice.
Observe that although the word "hear' in these verses cannot indicate that full "hearing" which it sometimes connotes (Matthew 10:14), yet it seems to mean more than merely listening, and to imply both a grasp of what is intended by the statements made and at least some acquiescence in their truth (Acts 2:22; Revelation 1:3; John 5:24).
According to the above explanation, it will be seen that in the imagery the rock represents practice; the sand, mere sentiment. There is thus a partial correspondence with the works insisted on by St. James in contrast to a bare orthodox faith (James 2:24). Assent is insufficient; there must be action.
Not uncommonly, indeed, the rock is considered to refer to the Lord himself, and the sand to human effort. Cf. Ford: "The parallel passage (Luke 6:48), where the words, 'cometh unto Me,' are inserted, indicates clearly the foundation of faith, the receiving the Lord Jesus as our Prophet, Priest, and King, which is the only basis on which good works can be built" (cf. even Allord). This, however, is hardly exegesis, but application, for the "coming to Christ" is in Luke only introductory to the hearing and doing, and is altogether omitted here. Although the statement is true in itself, it is only so far proper to this passage in that, apart from practice, there is (verse 23) no heart-union with Christ.