G0276–ἀμετάθετος–ametathetos

Wherein God, being minded to show more abundantly unto the heirs of the promise the immutability of his counsel, interposed with an oath;

ἀμετάθετον ametatheton “unchangeableness”

that by two immutable things, in which it is impossible for God to lie, we may have a strong encouragement, who have fled for refuge to lay hold of the hope set before us:

ἀμεταθέτων, ametathetōn “unchangeable,”