In Leviticus 25, what was Israel commanded to do every seventh year?

Answer: Let the land rest

The seventh year was a Sabbath of complete rest for the land, with no sowing of fields or pruning of vineyards.

“But in the seventh year there shall be a Sabbath of complete rest for the land—a Sabbath to the LORD. You are not to sow your field or prune your vineyard.”— Leviticus 25:4 (BSB)