Hear this word that the LORD has spoken against you, O people of Israel, against the whole family that I brought up out of the land of Egypt:
The Prophet wished doubtless by these words to confirm his own authority, for he saw that his doctrine was regarded with contempt: and it is probable that the words recited here were not only once delivered by him, but had been often repeated.
The scope of these verses is to convince the people of Israel that God had a controversy with them. That which the prophet has to say to them is to let them know that the Lord has something to say against them, Amo 3:1.
Commenting on Amos 3:1-8
Hear this word that the Lord hath spoken against you, O children of Israel,.... The prophecy against Israel begins in the preceding chapter, where notice is taken of their sins, at least some of them, and of their aggravated circumstances, and sure destruction; and here they are called upon to hearken and listen to what the Lord by his prophet had spoken, and was about...