שְׁתֵּ֣י יָדֹ֗ת לַקֶּ֙רֶשׁ֙ הָֽאֶחָ֔ד מְשֻׁלָּבֹ֔ת אַחַ֖ת אֶל־אֶחָ֑ת כֵּ֣ן עָשָׂ֔ה לְכֹ֖ל קַרְשֵׁ֥י הַמִּשְׁכָּֽן׃
Each board had two tenons, joined one to another. Thus did he make for all the boards of the tabernacle.
Read midrashic interpretation of Exodus 36:22: and classical rabbinic exegesis.