Siman 173

Our teacher, the Beit Yosef, wrote: "Mayim emtza'iyim are optional, and these words apply between one cooked food and another cooked food, but between a cooked food and cheese—they are obligatory." Thus far his words. And he was very brief and there is no understanding of this, and the matter is as follows: For at the end of the eighth chapter of Berakhot, the sages based mayim rishonim and mayim akharonim on verses, see there, and mayim emtza'iyim were not mentioned at all. However, in Chullin (105b) we say: "Mayim emtza'iyim are optional; Rav Nachman said: They only taught this between one cooked food and another cooked food, but between a cooked food and cheese—they are obligatory." And the Rashbam explained that between one cooked food and another cooked food refers to when both are of meat or both are of cheese, meaning that the washing is for mere cleanliness, but between a cooked food of meat and cheese that preceded it—it is obligatory, so that the cheese on his hands does not stick to the cooked food of meat. And Rabbeinu Tam explained that between one cooked food and another cooked food also means between a cooked food of meat and a cooked food of cheese, and the sages were not concerned about this. But between a cooked food of meat and cheese itself—it is obligatory, see there, and the Tur also explained it thus, see there.

And one should not ask, when there is an obligation to wash his hands, why they did not institute a blessing for this, for it can be said that this is like the preparation of food, such as removing forbidden fats and salting (Tosafot ibid. end of the heading starting with "Mayim"), and a blessing is not applicable to this. And behold, according to this, it does not belong at all to the laws of the meal but rather to the laws of meat and milk, and it was explained in Yoreh Deah siman 89. And in truth, the Rambam did not mention this in the laws of blessings, but rather in chapter 9 of Forbidden Foods, and he also did not mention there the language of "netilah" but rather "washing," see there, and according to this, the words of our teacher, the Beit Yosef, are interpreted according to both explanations. And he wrote further that between meat and fish it is an obligation to wash because it is harmful regarding tzara'at, and danger is more stringent than a prohibition. And there is a bit of proof for this from Pesachim (76b), and the Rambam did not mention this, and they wrote that now natures have changed (Magen Avraham), and also the Tosafot at the end of the first chapter of Moed Katan wrote something similar to this. And we do not eat fish after meat, only meat after fish, and we have heard that there are places where they eat meat and afterwards fish.

Our teacher, the Beit Yosef, wrote in section 3: "All matters that apply to the final waters apply to the middle waters, whether to be lenient or to be stringent, except for a lapse of attention which disqualifies in the middle waters, because he still desires to eat and his hands require guarding, and except for the drying of the hands, for the middle waters require drying like the first waters." Thus far his words. Our teacher, the Rema, added that there are those who said that middle waters specifically require water, which is not the case with the final waters, as will be seen below in siman 181, thus far his words, because other liquids do not clean the fat and the food, and there is one who disagrees regarding this (Magen Avraham in the name of the Rashal), and the drying is necessary because of filth (ibid.). And I do not understand how a lapse of attention is relevant to middle waters which are an interruption between milk and meat, and if it is because of a lapse of attention regarding the first waters, if so, how is this relevant to the middle waters? And it requires further study.