Numbers 35:30

The punishment of a murderer shall be based upon testimony; but no one shall be condemned upon the testimony of only one person

Other versions

King James Version

Whoso killeth any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.

English Standard Version

"If anyone kills a person, the murderer shall be put to death on the evidence of witnesses. But no person shall be put to death on the testimony of one witness.

New International Version

"'Anyone who kills a person is to be put to death as a murderer only on the testimony of witnesses. But no one is to be put to death on the testimony of only one witness.