'Three' in the Bible

Then Moses designated three cities on the east side of the Jordan,

"Every male must appear in the presence of the LORD your God three times a year at the place where he will choose: for the Festival of Unleavened Bread, the Festival of Seven Weeks, and the Festival of Tents. He must not appear in the LORD's presence empty-handed,

Based on the testimony of two or three witnesses, they must surely die. But they are not to die based on the testimony of one person.

You must reserve three cities within the land that the LORD your God is about to give you to possess.

Build roads throughout the land that the LORD your God is providing as an inheritance, and then divide it into three districts so that any killer may flee there.

Therefore I am commanding you to reserve three cities."

and if you are careful to observe all these commands that I am commanding you today to love the LORD your God and to walk daily in his ways then add three more cities in addition to these three cities.

"The testimony of one person alone is not to suffice to convict anyone of any iniquity, sin, or guilt. But the matter will stand on the testimony of two or three witnesses.