"to sanctify it": with a blessing — whence they ruled: It is sanctified by wine (i.e., "kiddush") upon its entry. This tells me only of kiddush at night. Whence do I derive (the same for)kiddush in the daytime? From "Remember the day of Sabbath." This tells me only of (kiddush for) the Sabbath. Whence do I derive (the same for) the festivals? From (Leviticus 23:4) "These are the festivals of the L–rd, which (including the Sabbath) you shall "call" (in the kiddush) in their times."
This Derivation Establishes Kiddush at Night, When Shabbat Begins
Mekhilta Tractate Bachodesh 7:10