וְהָיוּ֙ שְׁמֹנָ֣ה קְרָשִׁ֔ים וְאַדְנֵיהֶ֣ם כֶּ֔סֶף שִׁשָּׁ֥ה עָשָׂ֖ר אֲדָנִ֑ים שְׁנֵ֣י אֲדָנִ֗ים תַּ֚חַת הַקֶּ֣רֶשׁ הָאֶחָ֔ד וּשְׁנֵ֣י אֲדָנִ֔ים תַּ֖חַת הַקֶּ֥רֶשׁ הָאֶחָֽד׃
Thus there shall be eight boards, and their sockets of silver, sixteen sockets: two sockets under one board, and two sockets under another board.
Read midrashic interpretation of Exodus 26:25: and classical rabbinic exegesis.