Rashi on Numbers 17:21/רש"י על במדבר י״ז:כ״א

1בתוך מטותם [AND THE STAFF OF AARON WAS] IN THE MIDST OF THEIR STAVES — He placed Aarons staff in the middle (בתוך) in order that people should not say, “It is only because he placed it at the side where the Shechinah is that it blossomed” (Midrash Tanchuma, Achrei Mot 8 on אחרי מות).