The Mishna (35a) teaches that someone who prepares matzot to bring together with their sacrifice (korbanot like that brought by a Nazir – Bamidbar 6:15 – who is completing his nezirut or someone bringing a thanksgiving offering – Vayikra 7:12 – include halot matzot together with the animal sacrifice) cannot use them to fulfill the mitzva of matza on Pesah. If, however, someone prepared such matzot to sell to others, then they can be used for the mitzva on Pesah.
This very issue was the subject of a question that Rabbi Ilai asked Rabbi Eliezer, who did not know the answer. When Rabbi Ilai posed the question to Rabbi Yehoshua, he was quick to refer to the Mishna, which distinguished between the two cases – if the matzot were prepared by someone to accompany his sacrifice they cannot be used for Pesah but if they were prepared for sale then they can be used for Pesah.
When I [Rabbi Ilai] returned and recited these matters to Rabbi Eliezer, he said to me in excitement: By the covenant, these are the very matters that were stated to Moses on Mount Sinai. Rabbi Eliezer swore that this had been transmitted over the generations going back to Moses on Mount Sinai. Some say he spoke in astonishment: By the covenant! Are these in fact the matters that were stated to Moses on Mount Sinai? And doesn’t this require a reason? Since there is no explicit tradition in this regard, it is necessary to provide a reason for this distinction.
The Aruk understands that both statements end with a question mark. The first one is Rabbi Eliezer talking, and he questions whether Rabbi Yehoshua’s ruling was truly based on a reliable tradition. The second statement is said by Rabbi Yehoshua, who insists that the tradition is a reliable one, but that it still needs a good reason, since even well-established traditions need to make sense.
The Gemara concludes with Rabbah’s explanation of the ruling. If someone prepares the matzot to sell, he has not made a final decision on what their destiny will be. He hopes to sell them to someone who needs them for a sacrifice. At the same time he thinks to himself that if they are not sold, he can always use them as matzot for the upcoming Pesah holiday.