Chapter 7:24-29 The Two Foundations

7:24 Therefore whosoever heareth these sayings of Mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock:

Therefore whosoever heareth these sayings of Mine - That is, the excellent doctrines laid down before in this and the two preceding chapters. 

7:25 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock.
Whoever you are, and whatever you build, it will be tried. No matter how firm is the rock beneath you, the winds will blow, and the rains will pour down upon your building. Whether you are in a palace or in a hovel, trial and testing must and will come to you: “The floods came, and the winds blew, and beat upon that house,-

7:26 And every one that heareth these sayings of Mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand:

And every one that heareth - and doeth them not - Was there ever a stricter system of morality delivered by God to man, than in this sermon? 

He who reads or hears it, and does not look to God to conform his soul and life to it, and notwithstanding is hoping to enter into the kingdom of heaven, is like the fool who built his house on the sand. When the rain, the rivers, and the winds come, his building must fall, and his soul be crushed into the nethermost pit by its ruins. 

7:27 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it.
And the rain descended, and the floods came - Such builders, and such a building, cannot stand against the violent rain of Satan's temptations, the floods of the world's persecutions, the stream and rapid torrent of their own heart's lusts, nor the blowing winds of heresy and false doctrine, and much less the storms of divine wrath and vengeance. 

They are in a most dangerous condition; they cannot support themselves; they must fall, and great will be their fall; their destruction is inevitable, their ruin is irrecoverable.

7:28 And it came to pass, when Jesus had ended these sayings, the people were astonished at His doctrine:
The people were astonished at His doctrine; it being something new, and unheard of, what they had not been used to; and coming in the demonstration of the Spirit, and of power, it carried its own evidence along with it, wrought conviction in their minds, and obliged them to acknowledge the truth of it.

7:29 For He taught them as one having authority, and not as the scribes.

Having authority - They felt a commanding power and authority in His word, i.e. His doctrine.