Walk through Amos, verse by verse, with the great Bible Commentaries of Matthew Henry (1662 - 1714) & Adam Clarke (1760 - 1832)
7:13
But prophesy not again any more at Bethel: for it is the king's chapel, and it is the king's court. KJV
{ And thou shalt no more put to, that thou prophesy in Bethel, for it is the hallowing of the king, and
is the house of the realm.} Wycliffe's Bible
But prophesy not - at Beth-el - He must not speak against idolatry, because that was the king's religion; and he who speaks against the king's religion must be an enemy to the state.