Not just any testimony counted. God had a clear idea of who could be trusted to speak truth in matters of life and death.
This verse, and the surrounding legal context in Deuteronomy, implies that witness testimony wasn't a free-for-all.
Who Qualified?
While not explicitly detailed in this single verse, the broader Jewish legal tradition, as understood by commentators, excluded certain individuals from testifying. This included children, women, servants, friends, enemies, and those of ill repute.
The 'Why' Behind the Rule
This wasn't about discrimination in a modern sense, but about ensuring the reliability of evidence in capital cases. The goal was to prevent false accusations and ensure that convictions were based on solid, trustworthy accounts. The integrity of the judicial process, and the protection of life, depended on the credibility of the witnesses.