Menahot, Chapter Thirteen, Mishnah Nine
1) [If one said,] This ox shall be an olah, and it becomes blemished, he may, if he so desires, bring two with its price.
2) [If he said,] These two oxen are for an olah, and they become blemished, he may, if he so desires, bring one ox with their price.
a) But Rabbi forbids it.
3) [If he said,] This ram shall be an olah, and it becomes blemished, he may, if he so desires, bring a lamb with its price.
4) [If he said,] This lamb shall be an olah, and it becomes blemished, he may, if he so desires, bring a ram with its price thereof.
a) But Rabbi forbids it.
5) One who says, One of my lambs shall be holy, or one of my oxen shall be holy, and he had only two, the larger one is holy.
6) If he had three, the middle one is holy.
7) [If he said,] I specified one but I do not know which it was I specified, or [if he said,] My father told me [that he had specified one] but I do not know which it is, the largest one among them must be holy.
Section one: An animal that has become blemished cannot be sacrificed. If someone sets aside a specific animal to be a sacrifice and it becomes blemished, he is not liable to bring another animal in its stead. The animal is redeemed for money and the money is holy and it can be used for any holy purpose. Therefore, he can bring two smaller oxen in place of the original one.
Section two: So too, if he originally dedicated two oxen to be sacrifices and both became blemished, he can redeem them both and use the money to buy one, more expensive oxen.
Rabbi forbids in both cases. It seems that Rabbi holds that once a person has dedicated a certain number of animals to the Temple he must bring that specific number of animals. As in yesterdays mishnah, Rabbi rules more strictly than the other sages.
Sections three and four: These sections teach basically the same rule, expect instead of one or two oxen the examples are a ram (two years old) or a lamb (one year old).
Section five: Since he didnt specify that the smaller one of his lambs should be holy we can assume that he meant for the larger one to be holy and that is the one that he must bring.
Section six: In this case, where he doesnt specify which lamb he wishes to dedicate, we assume that he didnt want to be miserly and give the smallest one or be overly generous and give the largest one, but that he wanted to give the middle sized lamb.
Section seven: If he says that he did specify which lamb would be holy, but he doesnt remember, then we must be concerned that he did dedicate the largest lamb. Similarly, if his father told him that he dedicated a lamb but he doesnt remember which lamb his father told him, he must bring his largest lamb.