Holy Zohar text. Daily Zohar -289.

Tikkun 21 – 30

ש- בת Shabbat is built from the letter Shin, that represents the three columns and the three patriarchs. בת, means daughter.
Shabbat is the daughter of Binah and she receives its energy with the prayers of Shabbat. It is the time when the daughter, which is Malchut, is at the level of Binah and able to draw light for the whole week.

The availability of the light in Shabbat is like the time of the ten days between Rosh Hashanah and Yom Kippurim. Those days are at an elevated state that lead to Yom Kupur, when we have 5 prayers to receive the Binah light for the whole year.
Isaiah 40:22 “היושב על חוג הארץ” “He who sits on the circle of the earth”. This verse tells us that the Light is spread like a circle around Malchut and there is a proper and best time to connect and draw a specific light.