Dear Rabbi Simon,
Interesting Ask the Rabbi entry in last week’s KC [click Kesher Connections newsletter to see the Q&A]. Would whistling be OK or is this too close to a musical instrument?
TY for your Q. Always nice to see that people read the KC. Whistling is allowed on Shabbos, including whistling through the agency of one’s fingers or hands.
There are those who resist whistling at all times, as it is said to attract demons. The origin of this superstition seems to be Russian (and not necessarily Jewish, though it has made its way to Jewish circles). IMO one need not pay it any heed. (Nevertheless, the Chazon Ish is quoted [Orchot Shabbat 2:21:60] as opposing loud and shrill whistling in such a manner [ie though putting one’s fingers in his/her mouth] as it is crass behaviour [פריצותא].)
Rabbi Rashi Simon