Rashi on Psalms
You desired neither sacrifice nor meal offering on the day of the giving of the Torah, as the matter that is stated (in Exod. 19:5): “And now, if you will earnestly hearken to My voice, etc.,” and likewise (in Jer. 7:22) Scripture states: “For neither did I speak with your forefathers nor did I command them, etc., concerning a burnt offering or a sacrifice.” I said, (Lev. 1:2) “If...from among you,” but I did not require it as an obligation to burden you. The daily sacrifices and the additional sacrifices are only to bring Me pleasure, that I ordained and My will was performed, but it is a small matter.