In Judaism, the concept of Osek B'Mitzvah Patur Min Hamitzvah (Hebrew: עוסק במצוה פטור מן המצוה, rough lt. "engaged in commandment exempt from the commandment", or rather, in a more understandable translation, "one who is engaged in a commandment is exempt from another commandment [at the same time]") sometimes exempts one from performing a religious obligation while one is engrossed[1] in another religious obligation.
Q: Which Mitzvot 'exempt' us from performing others? In other words, does involvement in any Mitzvah exempt you, or only specific Mitzvot? A: Only those Mitzvot which take some type of focus and concentration.