Musar על נדה 121:60

Behold the story of Gedalia ben Achikam where it is clear to our eyes that due to his great Chasidut to not judge Yishmael ben Netanya negatively, nor to accept an evil report, he said to Yochanan ben Kareach "you are speaking falsely of Yishmael" (Yirmiyahu 40:16). What resulted from this? He was murdered, the Jews went into exile, and their last ember was extinguished. Scripture attributes the murder of these people as if Gedalyah himself murdered them, as our sages of blessed memory, said (Nida 61a) on the verse: "all the bodies of the men whom he had killed through Gedaliah" (Yirmiyahu 41:9).