Menachos, Chapter 4, Mishnah 14. In the previous Mishnah we learned that olive oil and frankincense are not placed on the minchas chotei (the meal offering of a sinner) or on the minchas kena'os (the meal offering of a suspected adulteress). Our Mishnah comes to teach that this is not a single all-inclusive prohibition, but rather two separate prohibitions, and the basis for this is spelled out in the verses.
The source of the two prohibitions in the verses:
The minchas chotei (Vayikra 5:11) - "Lo yasim aleha shemen" - he shall not place oil upon it, and afterward "v'lo yiten aleha levonah" - and he shall not put frankincense upon it. Here we have two separate prohibitions.
The minchas kena'os - a similar expression is used, "lo yitzok" - he shall not pour, referring to the pouring of oil, and further on the verse states explicitly "shemen... lo yiten... levonah" - oil... he shall not put... frankincense.
Therefore the Mishnah states: "V'chayav al hashemen bifnei atzmo v'al halevonah bifnei atzmah" - one is liable for the oil on its own and for the frankincense on its own. One who places olive oil and frankincense on a minchas chotei or on a minchas kena'os transgresses two separate Torah prohibitions, and in principle becomes liable to two sets of lashes, if he was properly warned and there were witnesses present.
The commentators disagree as to what exactly the liability depends on: is it the prohibition of offering the korban after it has been disqualified, or is it already incurred by the very act of placing the oil in the first place? In other words, does the liability apply even if after placing the oil the person reconsidered and said, "We have ruined it, let us start over," or only when he actually offered the disqualified korban?
A further discussion arises regarding the view of Rabbeinu Tam, who holds that from the moment the oil is poured into a minchas chotei or a minchas kena'os the minchah is disqualified, as the Mishnah itself will state explicitly further on. And since the minchah is already disqualified, adding frankincense to it is a meaningless act, for this is no longer a valid minchah, and therefore there is no second prohibition here. According to his view, one who places both of them at once may become liable for two prohibitions, but one who places oil first and afterward frankincense is liable for only one. However, the Rambam did not cite this ruling, and neither did Rashi, which implies that the halachah follows the Rambam - that one can become liable for two.
The status of the minchah after the oil or frankincense was placed on it:
The Mishnah continues: "Natan aleha shemen p'salah" - if he placed oil upon it, he has disqualified it. Even a single drop of oil placed in the minchah, whether in a minchas kena'os or in a minchas chotei, is enough to disqualify it. By contrast, "levonah - yelaktenah" - frankincense, he should gather it up: one who placed frankincense on the minchah has committed a transgression, but if he gathered it up and removed it, the minchah returns to its valid status. That is, it is forbidden to do so, but placing the frankincense on top of it does not disqualify the korban.
The Mishnah further states: "Natan shemen al sheyareha - ein bo lo saaseh" - if he placed oil on its remainders, there is no negative commandment involved. This refers to one who offered the minchas chotei properly, and since he took the kometz (handful) and burned it, the remainders were left for the kohen to eat. If the kohen then added oil to that flour of the minchas chotei, there is no Torah prohibition in doing so, since the korban has already been offered, and the prohibition was stated only prior to the offering. Here too the commentators disagree as to whether this means it is permitted to do so at the outset, or only that after the fact there is no prohibition.
A vessel on top of a vessel:
Finally, the wording of the verse is "lo yasim aleha shemen" - he shall not place oil upon it, meaning that oil may not be placed on top of it. From here one might have thought to consider a case in which two vessels were set one on top of the other: in the lower vessel is the minchas chotei, and in the upper vessel resting upon it is oil. It would seem that the vessel of oil is resting on top of the minchas chotei, and there is "oil upon it" here. The Mishnah comes and teaches that this is not the plain meaning of the verse and that this is not the law at all: "Natan k'li al gabei k'li - lo p'salah" - if he placed one vessel on top of another, he has not disqualified it. Setting a vessel full of oil on top of the vessel containing the minchah does not disqualify the korban, and it is enough to remove the upper vessel and continue the service of the korban in its proper order.
In summary: In this Mishnah we learned that regarding the minchas chotei and the minchas kena'os there are two separate prohibitions - one for the oil and one for the frankincense - as spelled out in the verses, and one who places both of them is liable for each one on its own. We also learned that the oil disqualifies the minchah, whereas the frankincense can be gathered up and the minchah returns to its valid status; that placing oil on the remainders after the offering is not included in the prohibition; and that setting one vessel on top of another is not considered placing oil on the minchah and does not disqualify it.