Rabbi Chiya explains that for the reason explained above, Shabbat is the connection of Yessod and Malchut as it says in Exodus 31:16;
“וְשָׁמְרוּ בְנֵי יִשְׂרָאֵל אֶת הַשַּׁבָּת לַעֲשׂוֹת אֶת הַשַּׁבָּת לְדֹרֹתָם בְּרִית עוֹלָם”
“’So the sons of Israel shall observe the sabbath, to celebrate the sabbath throughout their generations as a perpetual covenant.’”
The Torah mentions ‘covenant’ everywhere Yessod and Malchut come together.
“וְנָתַתִּי שָׁלוֹם בָּאָרֶץ וּשְׁכַבְתֶּם וְאֵין מַחֲרִיד וְהִשְׁבַּתִּי חַיָּה רָעָה מִן הָאָרֶץ וְחֶרֶב לֹא תַעֲבֹר בְּאַרְצְכֶם.”
“I shall also grant peace in the land, so that you may lie down with no one making you tremble. I shall also eliminate harmful beasts from the land, and no sword will pass through your land.”
‘Peace’ comes from Yessod. It represents peace in Malchut that is the aspect of home and in the world.
‘I will punish you , seven…’ (#48) is the suffering in Malchut that is the seventh. Yessod and Malchut come together here and that is also aspect of ‘covenant’.