Boyd’s Bible Dictionary:
The jealous husband brought his suspected wife before the priest, with her offering of barley meal, without oil or frankincense, in her hand
The priest took holy water in an earthen vessel in his hand and sprinkled it with the dust of the floor. Then the priest administered the oath to her. If she confessed to guilt she was compelled to drink the water, and stood accursed. If otherwise, she was allowed to go free (Num. 5:12-31).
Concise Bible Dictionary:
“To be inflamed.” The warm affection that cannot bear to see its loved one enticed by another, as a man is jealous of his wife (Num. 5:14); as Paul felt for the Corinthian saints (2 Cor. 11:2); and as God regarded the people and the land which He had chosen, and upon which He had placed His name (Psa. 39:5; Ezek. 39:25; Joel 2:18; Zech. 1:14; Zech. 8:2). “Jehovah, whose name is jealous, is a jealous God” (Ex. 34:14).
Moses speaks of Jehovah provoking Israel to jealousy by their seeing Gentiles coming into blessing. Paul also sought to do the same that they might be saved (Deut. 32:21; Rom. 10:19; Rom. 11:11,14).
THE IMAGE OF JEALOUSY, which provoketh to jealousy, was seen in a vision by the prophet, set up in the temple (Ezek. 8:3-5), as when Manasseh set up the graven image in the house of Jehovah (2 Kings 21:7); though doubtless by the scope of the prophecy reference is made to secret idolatry in connection with the service of the temple, and to secret idols in the hearts of those who were professedly the worshippers of God: such would assuredly provoke the jealousy of Jehovah.
THE LAW OF JEALOUSY, when a man suspected his wife of being unfaithful to him, is given in Numbers 5:11-31. The woman was required to drink bitter water, composed of “holy water,” in which was placed dust from the floor of the tabernacle (type of the Holy Spirit applying what death is, as God’s judgment of sin, by the word to the conscience). If she had been unfaithful it would be a curse to her. It pointed figuratively to the question of Israel’s unfaithfulness to Jehovah.