Jeremiah 29:28

For therefore he sent unto us in Babylon, saying, This captivity is long: build ye houses, and dwell in them; and plant gardens, and eat the fruit of them.

Cross-reference

Jeremiah 29:1-10 is the original letter containing this command; this verse quotes it.

Jeremiah 29:5 contains the identical command to build houses and plant gardens, directly quoted here.