According to the Hebrew Bible, Phinehas (also spelled Phineas, /ˈfɪniəs/; Hebrew: פִּינְחָס, romanized: Pinəḥās, Ancient Greek: Φινεές Phinees, Latin: Phinees) was a priest during the Exodus. The grandson of Aaron and son of Eleazar, the High Priests (Exodus 6:25), he distinguished himself as a youth at Shittim with his zeal against the heresy of Peor.

Displeased with the immorality with which the Moabites and Midianites had successfully tempted the Israelites (Numbers 25:1–9) to inter-marry and to worship Baal-peor, Phinehas personally executed an Israelite man and a Midianite woman while they were together in the man's tent, running a javelin or spear through the man and the belly of the woman, bringing to an end the plague sent by Yahweh to punish the Israelites for sexually intermingling with the Midianites.

Phinehas is commended by Yahweh in Numbers 25:10–13, as well as King David in Psalm 106 (Psalms 106:28–31) for having stopped Israel's fall into idolatrous practices brought in by Midianite women, as well as for stopping the desecration of Yahweh's sanctuary. After the entry to the land of Israel and the death of his father, he was appointed the third High Priest of Israel, and served at the sanctuary of Bethel (Judges 20:28).

The name "Phinehas" probably comes from the Egyptian name Pa-nehasi (pꜣ-nḥsj). According to the Oxford Companion to the Bible, "the Bible also uses Egyptian and Nubian names for the land and its people. ... For the Egyptians used to these color variations, the term for their southern neighbors was Neḥesi, 'southerner', which eventually also came to mean 'the black' or 'the Nubian'. This Egyptian root (nḥsj, with the preformative pʾ as a definite article) appears in Exodus 6.25 as the personal name of Aaron's grandson, Phinehas (= Pa-neḥas)". The Theological Wordbook of the Old Testament interprets the name to mean "the bronze-colored one".

The account appears immediately after the story of Balaam, who had been hired by the Moabite chieftain, Balak, to curse the Israelites. Balaam failed to do so, as Yahweh put words in his mouth of blessing for Israel, instead (the first prayer said by Jews as part of their daily prayer service comes from this exact text). Having failed to curse them, Balaam left for his own country. The Book of Numbers asserts a direct connection between Balaam and the events at Peor, stating that the Moabites "caused the children of Israel, through the counsel of Balaam, to commit trespass against the LORD in the matter of Peor".

Moses gave orders to kill all the idolaters, yet Zimri, the son of the Israelite prince Salu from the Tribe of Simeon, openly defied Moses and publicly showed his opinion to those standing at the Tabernacle entrance with Moses by going in to Cozbi, the daughter of the Midianite prince Sur. In a moment of great strength born of holy zeal, Phinehas went after them and ran them through with a spear. He thus "stayed the plague" that had broken out among the people, and by which twenty-four thousand of them had already perished.

Yahweh noticed that Phinehas showed loyalty and bravery for him. Yahweh decided not to destroy all of the children of Israel in anger because Phinehas had made atonement for their sins. Yahweh declared that Phinehas, and his sons' sons for all eternity, would receive divine recognition for this; a covenant of peace and the covenant of an everlasting hereditary priesthood.

The Christian book of Revelation mirrors this sentiment. Revelation describes Jesus as speaking to one of seven Christian churches: "Nevertheless, I have a few things against you: You have people there who hold to the teaching of Balaam, who taught Balak to entice the Israelites to sin by eating food sacrificed to idols and by committing sexual immorality."