Water freezes at a temperature of at least 32 F or below.
So you need to maintain your inside house temperature to at least above 32 F to prevent pipes from freezing.
Most furnace thermostats in houses only go down to 55 F to 50 F at the lowest so if you're gone to work or gone somewhere keep the heating on to at least the lowest setting on the thermostat.
if you have pets in the house it's best to keep the temperature to at least 60 F.
I use a programmable thermostat that I can set to lower the heat when I'm gone and then it turns the heat back up to 75 F before I get home so the house is warm when I arrive.
Never turn your heating off fully because frozen pipes can and will occur and you'll have a lot of water damage as well.
Also the house will be too cold to return too and take too long to heat back up.