Why David's Name Was Esteemed in Halakhah After His Marriage

"Then the princes of the Philistines went forth; and it came to pass, as often as they went forth, etc. [that his name was much esteemed]" (1 Samuel 18:30). Rabbi Yehudah son of Rabbi Simon said: His name became greatly esteemed in halakhah. How so? When the Philistines heard that David had taken a wife, they said: It is written in the Torah, "When a man takes a new wife, etc." (Deuteronomy 24:8) — behold, now is the moment that we should spring upon David, and he will be lost from the world. But they did not know that David is wise and expounds. How does he expound? In what case is this said? Regarding optional wars; but in a war of mitzvah, all go forth, even a bridegroom from his chamber and a bride from her canopy. Rabbi Yehudah says: Not so, but rather, in what case is this said? Regarding a war of mitzvah; but in a war of obligation, all go forth, even a bridegroom from his chamber and a bride from her canopy.