Ezekiel 21:2

Son of man, set thy face toward Jerusalem, and drop thy word toward the holy places, and prophesy against the land of Israel,

Drop thy word toward the holy places - the three parts of the temple: the courts, the holy place, and the holiest. If "synagogues" existed before the Babylonian captivity, as Psalms 74:8 seems to imply, they and the proseuchai (G4335), or oratories, may be included in the "holy places" here.