The Greek in John 17:17 that is typically translated in English as “your word is truth” is translated by the English translation by and Pakaluk (2021) as “The Word, your Word is truth.

Pakaluk explains (p. 230): “The Greek is stronger than ‘your word is truth’; it conveys the emphasis represented here. We capitalize ‘Word’ because we take this to be the logos, as at the beginning of John’s Gospel. As Augustine remarks, ‘The Father then sanctified them in the truth, i.e. in His Word the Only-Begotten, them, i.e. the heirs of God, and joint-heirs with Christ.”

See also Word / Logos.