Menachos 13:1-2

Menachos 13:1

If a person obligates himself to bring “isaron” (in the singular), he must bring one isaron; “esronim” (in the plural), he must bring two isaron. If he knows that he specified a quantity but he doesn’t remember what it was, he must bring 60 isaron (which is the maximum for an individual flour offering). If he merely obligates himself to bring a flour offering, he can bring whatever type he wants; Rabbi Yehuda says that he must bring an offering of fine flour because that’s the flour offering par excellence.

Menachos 13:2

If a person obligates himself to bring a flour offering, or some type of a flour offering, he must bring one (of any kind). If he obligated himself to bring flour offerings, of some type of flour offerings, he must bring two (of the five different types of flour offerings). If he knows that he specified a type but he doesn’t remember which type it was, he must bring offerings of all five types. If he knows that he specified a flour offering of “esronim” (plural) but he doesn’t recall the exact number, he must bring an offering of 60 isaron; Rebbi says that he must bring offerings of all the different numbers of esronim, i.e., 60 offerings ranging in size from one isaron to 60 isaron.