There is a common saying that whenever one mispronounces a word in tefila, a deformed malach is created that will testify against him in Beis Din shel Mala. Does anyone have source for this?
The only thing I could find was "R’ Pinchas said: “Through prayer we re-create the angel MeTaT every day anew. Therefore, one must be very careful not to skip a single word from the prayer, and every word must be said slowly and with concentration. And if, Heaven forbid, a person swallows the words and skips, he has created a demon … he has created a kind of angel without hands or feet, and then his body hurts him and he experiences all kinds of suffering, because that crippled angel that he created pursues him. … the letters of the prayer are chambers that are very far from one another, which is why it is so very difficult to pray. Because, really, a person is very far from true prayer. … Therefore, there is no need to look forward to any other experience of vitality than to just say the words slowly, even in a dry way, until eventually he will slowly warm up and feel more enthusiastic. (Therefore, someone who comes in the middle of the prayer has already lost out on so much, because the rest of the minyan started an hour earlier and has already managed to warm up. By the time the group gets to Baruch She’amar, they already can say it with some vitality and enthusiasm, and he has lost out on this)” REBBE PINCHAS SHAPIRA OF KORETZ (1726-1791)"