Charles Ellicott Commentary Ezekiel 16:51

"Neither hath Samaria committed half of thy sins; but thou hast multiplied thine abominations more than they, and hast justified thy sisters by all thine abominations which thou hast done." — Ezekiel 16:51 (ASV)

You have justified your sisters. —The same expression is repeated in the following verse. In both it is evidently used in a comparative sense. By the greatness of Judah’s sins even Sodom and Samaria were made to appear innocent in comparison.