Resources for Yevamos daf 99
1. The משנה says that if a כהן and an עבד get mixed up at birth and we don’t know who is who, the two of them can sell the תרומות that they separate and keep the money מספק. The ריטב"א here asks an unusual question. He asks in the name of יש מקשים why they are allowed to sell the תרומה when they have a חיוב דאורייתא to give תרומה to a כהן? It should be a classic case of ספק דאורייתא לחומרא? He answers that perhaps the חיוב נתינה is only on a ישראל ואדי and not on a ספק כהן. He also brings an alternate גירסא that actually says they are not allowed to sell the תרומה, but if they did they can keep the money. There is a somewhat similar תוספות in ב"ב דף פּ"א ע"ב ד"ה אלא. The גמרא there is talking about a ספק תרומות ומעשרות as well and תוספות implies in his second answer that if there is a real ספק דאורייתא about תרומה then you must give it to a כהן. The שערי יושר in שער ה׳ פּרק ז brings the שער המלך and רש"ש who ask a fundamental question: these ראשונים seem to be against tons of משנוית and גמרות that say clearly that when there is a ספק about any מתנות כהונה that you are פּטור form giving it to a כהן because of the principle of המוציא מחברו עליו הראיה. In other words, the חיוב נתינה of מתנות כהונה is based on a חשן משפּט obligation that the תורה awards to the כהן, not because of any בין אדם למקום obligation. For example, if you have a ספק בכור, the משנה in בכורות says that you don’t need to give it to a כהן מספק. So why in our case does is the ריטב"א bothered by the fact that these men who were mixed at birth are not giving their תרומה to a כהן ואדי מספק? The שערי יושר answers with a big חידוש: there is a fundamental difference between the obligation to give פדיון הבן, ראשית הגז, זרוע לחיים וקיבה etc. to a כהן vs the obligation to give תורמה to a כהן. When it comes to items that don’t grow in the ground, then it is just a חשן משפּט obligation of גזל השבט, so if the כהנים can’t prove they are entitled to it then you can keep it because of המוציא מחברו עליו הראיה. However, when it comes to things that grow from the ground, there the תורה gave a מצות נתינה that is בין אדם למקום. He explains it is like a מצות ביעור—you must get rid of the “הקדש” aspect of the fruit by making it the private property of the כהן. Therefore, if a person has a ספק if they owe תרומה they must give it מספק like any ספק דאורייתא לחומרא. However, if they sold it they can keep the money since the money itself is just the חשן משפּט חיוב and on that we would say המוציא מחברו עליו הראיה.
It is also fascinating to note that תוספות here in ד"ה ואם says that if these two people end up eating the תרומה by mistake, they must be מפריש the קרן וחומש for כפּרה reasons but can they keep the money. This is also reflected in תוספות in כתובות דף ל׳ ע"ב ד"ה זר who brings the ירושלמי that says that a כהן doesn’t even have the right to be מוחל and if you eat his תרומה by accident and he is מוחל you still must be מפריש the קרן וחומש and then you can keep it since he was מוחל. This is another example where תרומה has aspects that are בין אדם למקום and aspects that are בין אדם לחברו.
2. There is another שער המלך in הלכות מעשר פּרק א הל׳ ד that quotes רש"י on our משנה that says that the עבד וכהן who got mixed up can sell the תרומה and don’t have to give it to another כהן. He brings that the מהר"י בי רב brings from the רשב"א ממונפשלייר that there is a תקנה דרבנן that even a כהן must be מפריש תרומה and give it to a different כהן, lest he come to not even bother being מפריש it. The שער המלך asks that it seems clear from our משנה that this isn’t true for if it was, the two people who got mixed up would have to be מפריש the תרומה and give it to someone else! He answers that perhaps this תקנה was only made for a כהן ואדי who can actually eat it, but a כהן ספק who can’t eat it has no reason to forget to be מפריש.
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