Source, in full
c. 1928, in 'The Constructive Painting of Russian Artists and Constructivism', in K. S. Malevich, Essays on Art, ed. Troels Andersen, (transl. Xenia Glowacki-Prus & Arnold McMillin), London: Rapp & Whiting, 1969, vol. 2, pp. 74-84
Notes from Wikiquote
Malevich asked his students and followers to repeat this short sentence after him, during his teachings