Gleanings from Orthodox Christian Authors and the Holy Fathers

psalm131_11

An oath is a form of speech that bears its own guarantee of truth. It can have two functions: it is either a guarantee of truth for those who receive it, or else it forces those who are under oath not to tell a lie. Thus in the verse 'The Lord hath sworn in truth unto David, and he will not annul it' (Ps. 131:11), the security of the promise is confirmed by the oath. St. Gregory of Nyssa, Commentary on the Canticle, in From Glory to Glory.