Testament of Dan 6:2
Testament of the Twelve PatriarchsAnd now, fear the Lord, my children, and beware of Satan and his spirits. Draw near unto God and unto the angel that intercedeth for you, for he is a mediator between God and man, and for the peace of Israel he shall stand up against the kingdom of the enemy. Therefore is the enemy eager to destroy all that call upon the Lord. For he knoweth that upon the day on which Israel shall repent, the kingdom of the enemy shall be brought to an end.
Galatians 3:19
18 For if the inheritance is based on the law, it is no longer based on the promise, but God graciously gave it to Abraham through the promise. 19 Why then was the law given? It was added because of transgressions, until the arrival of the descendant to whom the promise had been made. It was administered through angels by an intermediary. 20 Now an intermediary is not for one party alone, but God is one. 21 Is the law therefore opposed to the promises of God? Absolutely not! For if a law had been given that was able to give life, then righteousness would certainly have come by the law.
Notes and References
"... The LXX in Job 9:33 had used the term to bemoan the absence of someone to officiate between man and God. Anthony Hanson unconvincingly posits Job 9:33 as the main background here (“The Mediator: 1 Timothy 2:5-6,” in Studies in the Pastoral Epistles [London: S.P.C.K., 1968] 56-64). Philo had made considerable use of µεσίτης and cognates in his voluminous speculations about the existence of various cosmic and angelic intermediaries between God and human beings. The Mithra cult and other Greco-Roman religions also made liberal use of the term in their various mediatorial theologies. See also the Testament of Dan 6:2 concerning angelic mediators which might have influenced Paul himself in Galatians 3:19-20. The term is predicated elsewhere of Christ (Hebrews 8:6; 9:15; 12:24) but with reference specifically to priestly sacrifice and thus not at issue in 1 Timothy 2:5-6 ..."
Brown, Peter Dunstan The Use of Ransom Language in 1 Timothy 2:1-7 and Titus 2:11-14 (p. 100) The Catholic University of America, 2014