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 in another religious obligation.
Extensions of the rule
The Talmud makes use of a similar concept in reference to those who are not yet actively engaged in a mitzvah (commandment) but also to those who are busy preparing to perform a mitzvah, with the comment that שלוחי מצוה (shluchei mitzvah, lit. "messengers of a precept") are similarly exempt from performing other religious obligations, such as sitting in a sukkah.
The Pnei Yehoshua comments that such exemptions are valid only for positive commandments, stating that one thoroughly engaged in a positive precept (such as burying the dead or learning Torah) would certainly not enable one to violate negative precepts (such as performing adultery or consuming non-kosher food).