Reference for Ezekiel 40:17

וַיְבִיאֵ֗נִי אֶל־הֶֽחָצֵר֙ הַחִ֣יצוֹנָ֔ה וְהִנֵּ֤ה לְשָׁכוֹת֙ וְרִֽצְפָ֔ה עָשׂ֥וּי לֶחָצֵ֖ר סָבִ֣יב ׀ סָבִ֑יב שְׁלֹשִׁ֥ים לְשָׁכ֖וֹת אֶל־הָרִֽצְפָֽה׃

Then brought he me into the outer court, and, lo, there were chambers and a pavement, made for the court round about; thirty chambers were upon the pavement.