Question: At my workplace, we Daven Shacharit and people generally punch into work after Davening. Some people, however, punch in before, and are on the clock during the Davening. Can they be counted in the Minyan and lead the Davening?
Answer: It is forbidden to fulfill Mitzvot during work time. The book "Mesillat Yesharim" (chapter 11) brings this exact example when discussing theft. The Ramchal said that if someone fulfills a Mitzvah during work time, it will not be considered a merit, but a transgression. If someone performs a transgression, it cannot be considered a Mitzvah. When a person steals wheat and makes bread and then recites a blessing, it is not a blessing, but a disgrace. What is the difference between stealing an object and stealing time? When someone steals an object and use it to perform a Mitzvah – "Saneigor Na'aseh Kateigor" – a defender becomes a prosecutor. Something which is generally used as a vehicle to reach Hashem is transformed into a vehicle for sin. The same applies to stealing time. There are three levels of performing a Mitzvah through a sin: 1. You fulfill a Mitzvah through a sin, and now have a Mitzvah and a sin. The sin does not cancel out the Mitzvah and vice versa. 2. The Mitzvah is canceled out because you performed it through a transgression. 3. The Mitzvah becomes a sin. We see in "Mesillat Yesharim" that when someone fulfills a Mitzvah during work time, his act is considered a sin. This appears to be the opinion of the Jerusalem Talmud in the chapter "Lulav Ha-Gazul – The Stolen Lulav" in Massechet Sukkah. It is possible that others disagree with the Ramchal on this point. If a person davens during work time and he is sinning, how then is it possible to count a sinning person in a Minyan? We are not saying that he is evil. A person is judged according to the majority of his actions. It is possible that despite this sin, he has many merits. At this moment, however, he is not davening, but sinning, and cannot be counted in a Minyan and, all the more so, he cannot lead the davening. How do we inform him of this? With great wisdom. Perhaps you can photocopy chapter 11 of "Mesillat Yesharim" and highlight the appropriate parts and give it out to everyone. I should add, however, that a short Mitzvah like Davening Minchah, which takes five to ten minutes, is permissible since you receive a break once in a while anyway. But Shacharit takes much longer.