פּירוש אויף במדבר 28:10

עלת שבת בשבתו lit., THE BURNT OFFERING OF A SABBATH ON ITS SABBATH — and not the burnt offering of this Sabbath on another Sabbath. Take the case that one had not offered the sacrifice on this Sabbath, I might think that he might offer two on the following Sabbath! However, it states “on its Sabbath’, thus showing that if its day (the Sabbath on which it had to be brought) be past, its (that Sabbath’s) offering is cancelled (Sifrei Bamidbar 144:2).

עולת שבת בשבתו, “the Sabbath burnt-offering on its Sabbath.” This means that the procedure is to take place on each Sabbath, as if the Torah had written דבר יום ביומו, “a daily procedure day by day” (Exodus 8,13).
על עולת התמיד, “in addition to (after) the daily total-offering.”

But not one Shabbos burnt-offering… You might ask: Why concerning Yom Tov does Rashi also not write that we do not bring the burnt-offerings of one Yom Tov on another Yom Tov? The answer is that this does not have to be taught, for it is obviously forbidden, given that each Yom Tov has a distinct name. However, each Shabbos is the same as another Shabbos and one might have said that this was permitted, thus Rashi informs us that it is forbidden. (Gur Aryeh) One cannot say that this only comes to exclude the burnt-offerings of Shabbos from being offered on Yom Kippur, for example the emurin of Shabbos that were left over until Yom Kippur, teaching that they should not be offered. However one could make up for the burnt-offerings of one Shabbos on another Shabbos. For if so, it should have written עולת שבת בשבת [lit. "the burnt-offering of Shabbos on Shabbos"]. What is meant by בשבתו ["on its Shabbos"]? Hear from this that the verse is saying [it shall be brought] on its Shabbos and not on another.

על עלת התמיד BESIDES THE CONTINUAL BURNT OFFERING — these two lambs are additional offerings for the Sabbath besides (על) those two lambs of the continual burnt offering. And this tells us that these additional offerings must be brought only between the two continual offerings (Sifrei Bamidbar 144:2). Similarly in the case of all additional offerings it is stated that they are to be brought על עלת התמיד to point to this deduction.