en_tn_condensed/zep/03/16.md

In that day

"At that time" or "When this happens." This phrase here refers to the time of peace and restoration that immediately follows the day of Yahweh.

say to Jerusalem ... Zion

The names of these cities here refer to the people who live in them. AT: "say to the people of Jerusalem ... people of Zion" (See: rc://en/ta/man/translate/figs-metonymy)

Do not let your hands falter

To feel weak or helpless is spoken of as if their hands became physically weak. Here "hands" represents the whole person. AT: "Do not become weak" (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-synecdoche)