Exodus 26:27 Midrash

וַחֲמִשָּׁ֣ה בְרִיחִ֔ם לְקַרְשֵׁ֥י צֶֽלַע־הַמִּשְׁכָּ֖ן הַשֵּׁנִ֑ית וַחֲמִשָּׁ֣ה בְרִיחִ֗ם לְקַרְשֵׁי֙ צֶ֣לַע הַמִּשְׁכָּ֔ן לַיַּרְכָתַ֖יִם יָֽמָּה׃

and five bars for the boards of the other side of the tabernacle, and five bars for the boards of the side of the tabernacle, for the hinder part westward;