I looked at the Otzar Chochmoh and found incredibly nearly 15 times throughout Shas that where the Aramaic word KOFOH (KUF PEY ALEPH) or something similar comes in Shas Rashi is Matriach himself to tell you it is Tzof and then brings this Possuk in Melochom Beys "VAYOTZOF HABARZEL" However when it comes to 2 specific places in Shas in Makkos 11a and Avodah Zoroh 56a Rashi DOES NOT bring this Possuk.
Why did he decide just in these 2 Rashis not to bring the Melochim Beys Possuk but so many other times he does. What is his Cheshbon/thought process
Boruch Kahan , London England
Add Eruvin 53b to the list of places where Rashi does not quote the Pasuk.
It seems that when the Gemara is discussing an object that literally is floating on water, Rashi prefers to bring the Gemara in in Sukah 53a (about the waters of the depths "floating up" above the groundwater, to drown the world), since that provides the clearest description for the term. I assume that he prefers to cite a reference from a Gemara to a Gemara, since the Gemara's intention there clearly reveals the intention of the Gemara at hand. (In Sukah there, Rashi indeed brings the Pasuk since there is no clearer Gemara to reference regarding the meaning of the word.)
But when the Gemara is not literally discussing an object floating on water (but rather hands placed on top of an animal, or a "Kaparah mi'Kufya, etc.), Rashi cites the Pasuk as the closest descriptor for the term.
Best wishes,
Mordecai Kornfeld