Parashas Bamidbar · Passuk 3:26
the hangings of the enclosure, the screen for the entrance of the enclosure that surrounds the Tabernacle, the cords thereof, and the altar—all the service connected with these.
Chabad.org — English translation + Rashi
Source: Arachin 11b.
English: “The Tabernacle and the altar” — Scripture compares the altar to the Tabernacle: just as the Tabernacle [boards] were ten cubits, so the altar was ten cubits.
In context: The hekesh supplies a source for the height of the outer altar.
Custom
Chazal derive the ten-cubit height of the altar from its juxtaposition with the Mishkan.