en_tn/jer/05/24.md

they do not say in their hearts

Here "their hearts" represent their thoughts, and "say" represents thinking. Alternate translation: "they do not think" (See: rc://en/ta/man/translate/figs-metaphor)

keeping the fixed weeks of the harvest for us

Here "keeping the fixed weeks of the harvest" represents making sure that those weeks happen at the right time. Alternate translation: "making sure for us that the weeks of harvest happen when they are supposed to" (See: rc://en/ta/man/translate/figs-explicit)