Walk through Amos, verse by verse, with the great Bible Commentaries of Matthew Henry (1662 - 1714) & Adam Clarke (1760 - 1832)
3:2
You only have I known of all the families of the earth: therefore I will punish you for all your iniquities. KJV
{Only I knew you of all the kindreds of earth; therefore I shall visit on you all your wickednesses.}
Wycliffe's Bible
You only have I known - I have taken no other people to be my own people. I have approved of you, loved you, fed, sustained, and defended you; but because you have forsaken me, have become idolatrous and polluted, therefore will I punish you. And the punishment shall be in proportion to the privileges you have enjoyed, and the grace you have abused.