For the day of the LORD is near upon all the heathen: as thou hast done, it shall be done unto thee: thy reward shall return upon thine own head.
For - resumptive in connection with Obadiah 1:10, wherein Edom was threatened with cutting off forever.
The day of the Lord - the day in which He will manifest Himself as the Righteous Punisher of the ungodly peoples (Joel 3:14). The "all" shows that the fulfillment is not exhausted in the punishment inflicted on the surrounding nations by the instrumentality of Nebuchadnezzar; but, as in Joel 3:14, and Zechariah 12:3, "Then shall the Lord go forth and fight against those nations," that the last judgment to come on the nations confederate against Jerusalem is referred fight against those nations," that the last judgment to come on the nations confederate against Jerusalem is referred to.
As thou hast done, it shall be done unto thee. The righteous principle of retribution in kind (Leviticus 24:17; Matthew 7:2; cf. Judges 1:6-7; Judges 8:19; Esther 7:10).
Thy reward shall return upon thine own head - "thy reward," the reward of thy deed (cf. Isaiah 3:9-11).