Unlocking Bold 9930 from Sprint for Use on Verizon

I switched to Verizon from Sprint to buy the z10, but kept my Sprint Bold 9930. I'd like to unlock my Bold and insert the sim card from my Verizon z10. I need to know if this will work as I do not want to damage either device, but would rather go back to the Bold without having to purchase a new one from Verizon. Thanks!

You can't use a Verizon SIM in a Sprint phone. The Verizon SIM is for LTE, and the Sprint 9930 doesn't do LTE. Even then, you can't make a Verizon phone work on Sprint, or vice versa.