Amos called all the Israelites to hear a message from their Lord. He referred to them as those whom Yahweh had redeemed from Egypt, reminding them of the unique privilege they enjoyed. He also mentioned that the Israelites, among all the peoples of the world, had a special relationship to the Lord. "You only" is in the emphatic first position in the Hebrew sentence. This is an allusion to the covenant that God had made with the Israelites at Mt. Sinai (cf. Exodus 19:3-6; Deuteronomy 28:1-14). God had chosen (known, Heb. yada"; cf. Jeremiah 1:5) the Israelites in that He had made a commitment to them as His vassal in a covenant relationship. [1] He had also revealed Himself to the Israelites as He had done to no other people. God said He would punish His people for their iniquities because they were sins against His unusual blessings (cf. Amos 3:14). Greater privilege always results in greater responsibility (cf. Luke 12:48). Amos 3:2; Amos 3:14 both contain promises that God would punish His people, forming an inclusio or literary envelope around the whole passage. [source][source][source]
"A similar injunction to hear what God has to say formerly introduced his commands in the Sinai covenant. Now, it introduces his covenant lawsuit against his rebellious people, who are in fact his family." [2][source]