Menachos 4:5-5:1

Menachos 4:5

The Kohein Gadol’s daily flour offering didn’t come in halves. Rather he brought an isaron (one-tenth of an ephah) and divided it, offering half in the morning and half in the afternoon. If a kohein brought the morning half and died, and another kohein was appointed to replace him, the replacement should not bring half an isaron of flour from his home (as the Kohein Gadol would normally do), nor should he offer the second half-isaron of the kohein who died. Rather, he brings a whole isaron and divides it. He then offers half of it and half goes unused. In this way two halves are offered and two halves go unused. Rabbi Shimon says that if no replacement kohein was appointed, flour from the people was offered; Rabbi Yehuda says flour from the deceased kohein’s heirs; in either case, a whole isaron of flour was offered.

Menachos 5:1

All flour offerings are offered unleavened except for the leavened loaves that accompany thanksgiving offerings and the two loaves of Shavuos, which are leavened. Rabbi Meir says that he removes the leaven from them and uses it to leaven the flour offering; Rabbi Yehuda says that this is not the preferred method. Rather, he brings the leaven from elsewhere and puts it into the measure, which he then fills with flour. The Sages said to Rabbi Yehuda that following his method would cause the measure of flour to be too little or too much.