1)
What is "Melachah ha'Chitzonah"?
1.
Rashi: This is of the Bayis, e.g. buildings of Bedek (to strengthen) ha'Bayis, and wood for the Ma'arachah, which they brought from outside.
2.
Ibn Ezra: It is work from outside the city, for the needs of Beis Elokim.
