Spitting during Aleinu

Why Do Some People Spit When Reciting Aleinu

Shalom!

Thank you for your question.

Indeed, some people have the custom to spit at the words "shehem mishtachavim l'hevel varik umitpallelim el el lo yoshia" ("they bow down to nonsense and worthlessness and pray to a God who does not save")  when reciting the Aleinu prayer. (1) It is explained that spitting after reciting this passage demonstrates one's abhorrence for idolatry. Furthermore, since speech automatically stimulates saliva, spitting at this point shows that one does not want to benefit from idolatry in any way, not even from the saliva produced at its mention!

One who chooses to spit during Aleinu should do so into a tissue or onto the ground and then immediately rub it away with one's foot so that it is not noticeable. Most authorities, however, question the authenticity and legitimacy of this custom entirely, calling it "the custom of imbeciles". (2) It is also noted that some people were spitting at the wrong passages. (3) 

Spitting during Aleinu was also seen by some rabbinic leaders as an unnecessary provocation of the Christians. (4) This was based on the false claim that "they bow down to nonsense and worthlessness and pray to a God who does not save" was referring to the Christian prophet. Rather, it actually refers to ancient pagan idolatry. So too, spitting in a synagogue is disrespectful and possibly even forbidden according to halacha. (5) It is said that the kabbalists, including the Arizal, were very particular never to spit at all.

Nevertheless, there are a number of authorities who justify the practice and a number of Chassidic communities conduct themselves accordingly. (6) Those who regularly spit regularly when reciting Aleinu should not do so when reciting it as part of the silent Mussaf on Rosh Hashana. (7)

1 Minhag Chabad and others.

2 Mekor Chaim 132:2

3 Kitzur Shla p.132.

4 Mekor Chaim 2:97.

5 Kitzur Shulchan Aruch Mekor Chaim 8:15.

6 Taz, YD 179:5.

7 OC 97:2.