For he did not know what he was saying, because they were terrified.
This brief explanation has deep meaning. When a person encounters the true presence of God, he often loses the measure and accuracy of speech. Peter’s words came not from calm reflection, but from amazement and fear. Before the holy presence, human language grows poor. This is not merely fear, but sacred awe that a person feels when he stands before heavenly glory. The disciples were seeing what is usually hidden from human eyes, and their confusion was natural. This verse also teaches that in moments of great revelation a person should not hurry to consider his words precise. Before the mysteries of God, humble silence is often deeper than hastily spoken words.