Strong's Greek #3315 - μεσιτεύω mesiteuó (to interpose)

confirm.

From mesites; to interpose (as arbiter), i.e (by implication) to ratify (as surety) -- confirm.

see GREEK mesites

Strong's 3315: μεσιτεύω

μεσιτεύω: 1 aorist ἐμεσίτευσα; (μεσίτης (cf. Winer's Grammar, p. 25 e.));

1. to act as mediator, between litigating or covenanting parties; translated as to accomplish something by interposing between two parties, to mediate, (with the accusative of the result): τήν διαλυσιν, Polybius 11, 34, 3; τάς συνθήκας, Diodorus 19, 71; Dionysius Halicarnassus 9, 59; (cf. Philo de plant. Noë, 2:2 at the end).

2. as a μεσίτης is a sponsor or surety (Josephus, Antiquities 4, 6, 7 ταῦτα ὀμνυντες ἔλεγον καί τόν Θεόν μεσιτην ὧν ὑπισχνουντο ποιούμενοι (cf. Philo de spec. legg. 3:7 ἀοράτῳ δέ πράγματι πάντως ἀόρατος μεσιτευει Θεός etc.)), so μεσιτεύω comes to signify to pledge oneself, give surety: ὅρκῳ, Hebrews 6:17.

Strong's Greek: 3315. μεσιτεύω (mesiteuó) — 1 Occurrence

Hebrews 6:17 - V-AIA-3S
GRK: βουλῆς αὐτοῦ ἐμεσίτευσεν ὅρκῳ
NAS: of His purpose, interposed with an oath,
KJV: counsel, confirmed [it] by an oath:
INT: counsel of him he guaranteed by an oath