Peace be upon you. Regarding the ruling of Ayatollah Khamenei on the matter of multiple intermediaries in impurity, is there a reference that states the second contaminated object does not cause impurity, to which we can refer?
And the answer is as follows:
Ayatollah Sistani (may Allah preserve him):
The object contaminated by direct contact with impurity is considered impure and will contaminate anything it touches if moisture is present. Similarly, an object contaminated by contact with another contaminated object will also contaminate what it touches, provided there are no multiple intermediaries between it and the original source of impurity; otherwise, it does not cause impurity, although it is recommended to avoid it. For example, if the right hand touches urine, it becomes impure. If the left hand then touches the right hand with moisture, it is also ruled impure. Likewise, if the left hand then touches something else, like a garment, with moisture, it is ruled impure. However, if the garment touches something else with moisture, whether liquid or solid, it is not ruled impure.
Ayatollah Khamenei (may Allah preserve him):
The object that touches the source of impurity becomes impure, and if it touches a pure object with moisture, the latter becomes impure. Likewise, if this contaminated object touches another pure object with moisture, it is obligatory to consider it impure; however, the object that touches this third contaminated object does not become impure.
Ayatollah Sheikh Wahid Khorasani (may Allah preserve him):
An object contaminated by direct contact with impurity is like the impure object; it contaminates what it touches with moisture. Similarly, an object contaminated by contact with another contaminated object will contaminate a small amount of water it touches. However, for larger amounts, the ruling on impurity in the second and third intermediaries is based on caution, and for more than that, caution is preferred.
Ayatollah Sheikh Ismail Fayyad (may Allah preserve him):
You may ask whether the second contaminated object, which is contaminated through one intermediary between it and the source of impurity, contaminates what it touches. The answer is that it does not contaminate, according to the more apparent ruling, if the intermediary between it and the source of impurity is solid and not liquid.
For example, if a garment touches a corpse with moisture, and then your hand touches the garment while it is still moist, your hand becomes the second contaminated object in the sequence of contamination. However, if the bedding then touches your hand with moisture, does it become contaminated? The answer is that it does not become contaminated, according to the more apparent ruling, since there are two intermediaries between it and the source of impurity: the garment and your hand. Thus, impurity does not transfer through two intermediaries. This is the meaning of saying that the first contaminated object causes impurity, while the second does not. The first contaminated object is directly contaminated by the source of impurity, while the second is contaminated through one intermediary.
Another example: A small amount of water touches a corpse, then the water touches a garment, and subsequently the garment touches the bedding with moisture. In this case, there are two intermediaries between the bedding and the source of impurity: the small amount of water and the garment. Since the first intermediary is liquid, it does not count as an intermediary, and it is as if there is only one intermediary between the bedding and the source of impurity, which is the garment. Therefore, impurity extends from the source of impurity to what it touches through one intermediary, but it is preferable to exercise caution.
Ayatollah Sheikh Nasser Makarem Shirazi (may Allah preserve him):
If something becomes impure, for example, if the hand touches urine, and then it touches something pure with moisture, that object also becomes impure.
May you be successful in all good.