Then stood up Phinehas, and executed judgment - Inflicted summary punishment upon a principal offender. Numbers 25:7-8.

Then stood up (r) Phinehas, and executed judgment: and [so] the plague was stayed.
(r) When all others neglected God's glory, he in his zeal killed the adulterers and prevented God's wrath.

Then stood up Phinehas, and executed judgment,.... When none else would, he rose up in great zeal for the Lord of hosts; and took on him the work of a civil magistrate, and slew two persons of noble birth in the very act of fornication. The Targum is,
"he prayed''
and so the Syriac version
"he interceded with the Lord, that the plague might stop.''
This he might do, as well as the other, though it is not elsewhere recorded, and in which he succeeded: but in the Talmud (y) it is observed that it is not said (that is, "he prayed"), but from whence may be learned, if it is proper to say so, that he executed judgments with his Maker. The Septuagint and Vulgate Latin versions render it, "he appeased"; made atonement for propitiation; and this is said of him, Numbers 25:13.
And so the plague was stayed; it was restrained from proceeding further; no more execution was done by it. In this he was a type of Christ, who, by doing righteousness, by the atoning sacrifice of himself, and by his intercession, has appeased the wrath of God, and satisfied divine justice so that there is no condemnation to them that are interested in him; no evil of punishment shall befall them, nor plague come nigh them.
(y) T. Bab. Sanhedrin, fol. 82. 2.

stood--as Aaron "stood between the living and the dead, and the plague was stayed" (Numbers 16:48).
executed judgment--literally, "judged," including sentence and act.