Rashi explains why Pinchas, and not Elazar, led the army in battle against Midyan. Hashem said that he who initiated the mitzvah, who originated the vengeance against this abominable nation, should complete the task. Pinchas, who slew Kosbi, should finish the job. What is the reason that “he who begins the mitzvah” is told to complete it? Horav Chaim Shmuelevitz, zl, comments that there is no comparison between an endeavor which is executed piecemeal and one which is performed in one complete unit. A number of people participating in a mitzvah – one after another – demonstrates the beauty of teamwork. Such a cooperative effort, however, is still not to be compared to the quality manifest when one performs the entire mitzvah by himself. A mitzvah performed in sections, one that is carried out in components, does not have sheleimus, completeness/ perfection. Sheleimus can be achieved only if a mitzvah is carried out by one person in one motion.
When Rabbi Akiva returned after twelve years of study with an entourage of twelve thousand students, crowds gathered to see the great Torah scholar. His wife, who had encouraged his decision to leave home to study Torah, was also waiting. As Rabbi Akiva came close, one of the women questioned his wife about how she had permitted him to stay away for so many years. Rabbi Akiva’s wife responded emphatically, “I would be happy to let him return for another twelve years!” Rabbi Akiva heard this and immediately turned around to return to the yeshivah to study. He returned twelve years later with twenty four thousand students. The question which begs elucidation is apparent: Why did Rabbi Akiva not stop for even a moment to greet his wife, from whom he had been separated for twelve years? Would it have been such a terrible thing to do? The response which is echoed by the various baalei mussar, teachers of ethical behavior, is that two times twelve is not nearly the same as one continual period of twenty-four uninterrupted years. What Rabbi Akiva achieved in Torah study, his brilliant erudition, his vast group of students, was due to the fact that he had studied continually for twenty-four years. He did not pause; he did not take a break; he would not even say hello to his wife after twelve years! He did not weaken his momentum. A brief interlude quells one’s enthusiasm, diminishing the end result. One who begins a mitzvah should complete his action to achieve greater success.