I am looking for a list of sources (early Rishonim and before) explicitly claiming that G-d is perfect.
One place I found is Devarim 32:4 "The deeds of the [Mighty] Rock are perfect, for all His ways are just; a faithful God, without injustice He is righteous and upright." This is not exactly perfection of G-d, just perfection of His work (good enough for me, but perfection of G-d is preferable). The Sifri on this verse spells it out explicitly.
Another is the description of the 2nd of 13 Principles of Rambam in the introduction to the Perek Cheilek in Maseches Sanhedrin, in his commentary on the Mishnah. He spells it out clear there (interestingly, in the siddur an equivalence is used - His Uniqueness - but I want it to mention perfection explicitly).
Thank you very much.
EDIT A question was raised which word in lashon hakodesh is being sought precisely. A variant of the word שלם shalem (e.g. שלמות sheleimus) would be ideal, but תם tam or תמים tamim would be ok too.