Walk through Amos, verse by verse, with the great Bible Commentaries of Matthew Henry (1662 - 1714) & Adam Clarke (1760 - 1832)
9:4
And though they go into captivity before their enemies, thence will I command the sword, and it shall slay them: and I will set mine eyes upon them for evil, and not for good. KJV
{And if they shall go away into captivity before their enemies, there I shall command to sword, and it
shall slay them. And I shall put mine eyes on them into evil, and not into good.} Wycliffe's Bible
I will set mine eyes upon them for evil - I will use that very providence against them which before worked for their good. Should they look upward, they shall see nothing but the terrible lightning-like eye of a sin-avenging God.