וְאַרְבָּעִ֥ים אַדְנֵיהֶ֖ם כָּ֑סֶף שְׁנֵ֣י אֲדָנִ֗ים תַּ֚חַת הַקֶּ֣רֶשׁ הָֽאֶחָ֔ד וּשְׁנֵ֣י אֲדָנִ֔ים תַּ֖חַת הַקֶּ֥רֶשׁ הָאֶחָֽד׃
And their forty sockets of silver: two sockets under one board, and two sockets under another board.
Read midrashic interpretation of Exodus 26:21: and classical rabbinic exegesis.