Is it permitted for you say amen to his brachos before you wash neggel vasser [נטילת ידים]? We know that until neggel vassar one shouldn't do anything [except say מודה אני]. No getting dressed, going to the bathroom [unless one really has to go] or anything else. Neggel vassar is the first thing you do.
This question was discussed in the sefer She'elas Shaul Vol. 2 Simman Yud [written by Rabbi Shaul Breish a Rav in beautiful Zurich] and he said as follows: The Rema [סימן פד] says that in a bathhouse [do you believe that until quite recently people didn't have private bathrooms and showers and the bathhouse were communal!] one may not say amen, so apparently the same would apply to answering amen with unclean hands. However there is a distinction - One is not even allowed to think divrei torah in a bathhouse whereas before negel vassar one is permitted to think divrei torah, so perhaps saying amen is also permitted.
On the other hand [pun inteeeended] when one says amen it is as if he is saying the bracha itself as the gemara says in Shavuos [29b] that saying amen after an oath is as if the person himself took the oath. So maybe saying amen is considered more than just thinking and is therefore prohibited.
Not so simple - one can argue that saying amen counts as if he made the bracha ONLY if he intends to be yotzei with the bracha but in our case the person who just woke up doesn't intend to be yotzei, so maybe it is permitted.
This brings us to the ruling of the Rema [סימן קסז ב] who says that when one makes a bracha he should have kavana that the amen of those answering should also be part of his bracha [the Yerushalmi says that amen is part of the bracha - see the Gra there]. So perhaps it would be forbidden to answer amen because it is considered part of the bracha.
Rabbi Breish concludes that one should be stringent and refrain from answering amen [and quotes the Bochachter Rov who asks this very question and doesn't come to a clear conclusion].
Sweet friends - Rabbi Breish is a MUCH greater man than I but I beg to differ. תורה היא וללמוד אני צריך.
Let's start at the beginning. From whence the premise that one is not allowed to make brachos before neggel vassar. If you open up a gemara brachos [דף ס] you will see a discussion of the order of brachos we make in the morning and lo and behold the gemara implies very strongly that various brachos are made BEFORE negel vassar. Most rishonim understand the gemara that way including the Shulchan Aruch [סימן ד סעיף כג]. The only thing one may not say before negel vassar is krias shma and davening but brachos are permitted. So if one is allowed to say a bracha with Hashem's name one is certainly permitted to answer amen.
One caveat - if ones hands are PHYSICALLY dirty in the morning then he must clean them before saying amen [look in the aforementioned Shulchan Aruch in סימן ד].
In fact Rav Ovadiah Yosef has an extremely lengthy teshuva [יביע אומר ח"ד סי' ב-ד] where he discusses the question of whether a person who gets up in the middle of the night and wants to drink a glass of water needs to wash. He concludes that it is not necessary because as we explained one is allowed to make brachos before negel vassar. עיין שם!!!! [The Zohar Hakadosh is VERY VERY strong in his insistence that nothing be done before neggel vassar but this seems to be against the gemara and codified halacha].
I will add that it a very serious infraction to hear a bracha and not answer amen so [unlike what Rabbi Breish said] the stringency would be to answer amen.
I am quite confident that if Rabbi Breish had seen the teshuva in the Yabia Omer he would have ruled differently.
Or maybe not...
