Rashi on Numbers 11:28/רש"י על במדבר י״א:כ״ח

1כלאם — (This is taken as the equivalent of כַּלֵּם, “destroy them”, “make an end of them”; cf. Rashi on Exodus 17:9) — He meant: cast upon them the responsibility for public affairs and they will of themselves soon come to an end (through the worry and anxiety this entails). — Another explanation is: that the word means put them into prison (כלא). He said this because they were prophesying, “Moses will die and Joshua will bring Israel into the Land” (cf. Sifrei Bamidbar 96; Sanhedrin 17a).