Parashas Bamidbar
וְקַלְעֵ֣י הֶֽחָצֵ֗ר וְאֶת־מָסַךְ֙ פֶּ֣תַח הֶֽחָצֵ֔ר אֲשֶׁ֧ר עַל־הַמִּשְׁכָּ֛ן וְעַל־הַמִּזְבֵּ֖חַ סָבִ֑יב וְאֵת֙ מֵֽיתָרָ֔יו לְכֹ֖ל עֲבֹדָתֽוֹ׃ {ס}
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.
Torah Temimah points to Zevachim / TT (verified).
על המשכן ועל המזבח — מקיש מזבח למשכן: מה משכן י׳ אמות אף מזבח י׳ אמות.
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.
Custom
Chazal derive the ten-cubit height of the altar from its juxtaposition with the Mishkan.