Hebrews 6:13

13ΤῷForγὰρto AbrahamἈβραὰμhaving made His promiseἐπαγγειλάμενοςὁGodθεός,sinceἐπεὶbyκατ’no oneοὐδενὸςHe hadεἶχενgreaterμείζονοςto swearὀμόσαι,He sworeὤμοσενbyκαθ’Himselfἑαυτοῦ,

For God, having made the promise to Abraham, since He had no one greater to swear by, He swore by Himself,