Parallel
Romans 8:16
Nestle 1904 Greek New Testament · Berean Standard Bible
αὐτὸ τὸ Πνεῦμα συμμαρτυρεῖ τῷ πνεύματι ἡμῶν ὅτι ἐσμὲν τέκνα Θεοῦ
The Spirit Himself testifies with our spirit that we are God’s children.