Kia haumaru (kee how-mar-oo)
This literally translates to "be healthy" or "be well," but it's often used in a similar way to "be safe" in English, especially when saying goodbye.
Here are some other ways to express similar sentiments in Māori:
* Kia kaha (kee ka-ha) - Be strong.
* Kia manawanui (kee man-a-wan-oo-ee) - Be patient.
* Kia ora (kee oh-ra) - Be well.
* Arohanui (a-ro-ha-noo-ee) - Much love.
The most appropriate phrase will depend on the context and the relationship you have with the person you're speaking to.