I've heard you shouldn't say the names of angels, except for the four that surround us at night.
What's the source and reason for this? Is it halacha or kaballah?
The Kitzur Shulchan Aruch (129:15) says to be very careful not to say the names of the angels concerning the "yehi ratzon" after blowing the shofar. According to kipa.co.il, the reason to not say the name is because the name is just a symbol for the angel but not its actual name, but the author of that web page says there's no punishment for saying it. I searched and didn't find a distinction between the four angels that surround us at night.