Zohar Ha’azinu- Idra Zuta
Malchut was separated from the rib, which is the side of Zeir Anpin in a sawing process to come face to face with him. When they are joined together they look like one because they are the Right and Left from the same level.
We learn from that the soul of a male is like half of a body, meaning half of the soul. The right side, male, is Chessed and the Left side is female, Gevurah.
When the two sides are together the upper worlds are filled with joy because they are blessed from the body in its complete state.
“עַל כֵּן בֵּרַךְ יְהוָה אֶת יוֹם הַשַּׁבָּת וַיְקַדְּשֵׁהוּ”
“Therefore YHVH blessed the Sabbath day and hallowed it.”
On Shabbat, there is a complete unification between the male and female and they become one body. When that happens, YHVH brings blessings because blessings can come only to a complete vessel.
The beauty of the female comes from the beauty of the male. The female, Malchut is the root of the three worlds of B’riah, Yetzirah, and Asiyah. Malchut is like the mother that all receive from her and go back to her. Binah is the mother to the body that is Zeir Anpin that receives everything from her.
Binah nourishes Zeir Anpin and the unification of Z”A and Malchut draws lights of blessings that benefit the lower three worlds. Without this unification, the lower worlds are like empty vessels.