Commentary for Megillah 26:11

אמר לו והלא אין משמרתי ומשמרתך שוה אמר לו אני אשמור משמרתי ומשמרתך והיינו דכתיב ויבקש הדבר וימצא שלא נמצאו במשמרתן

One said to the other: But are not my post and your post different? He replied: I will keep guard at my post and you at yours. So it is written, "And in inquisition was made and it was found" (Esther 2:23) that is to say, they were not [both] found at their posts.

Rashi on Megillah