en_tn/jer/33/20.md

Yahweh says

Yahweh is speaking of himself here. Alternate translation: "I say" (See: rc://en/ta/man/translate/figs-123person)

If you can break my covenant with day and night ... proper times

This phrase starting with "If" is a contrary-to-fact condition in which Yahweh speaks of something that the people cannot possibly do. (See: rc://en/ta/man/translate/figs-hypo)