2 Enoch 49:3
Secrets of Enoch1 I swear to you, my children, but I swear not by any oath, neither by heaven nor by earth, nor by any other creature which God created. 2 The Lord said: There is no oath in me, nor injustice, but truth. 3 If there is no truth in men, let them swear by the words, Yea, yea, or else, Nay, nay. 4 And I swear to you, yea, yea, that there has been no man in his mother’s womb, (but that) already before, even to each one there is a place prepared for the repose of that soul, and a measure fixed how much it is intended that a man be tried in this world. 5 Yea, children, deceive not yourselves, for there has been previously prepared a place for every soul of man.
Matthew 5:34
33 “Again, you have heard that it was said to an older generation, ‘Do not break an oath, but fulfill your vows to the Lord.’ 34 But I say to you, do not take oaths at all—not by heaven, because it is the throne of God, 35 not by earth because it is his footstool, and not by Jerusalem, because it is the city of the great King. 36 Do not take an oath by your head because you are not able to make one hair white or black. 37 Let your word be ‘Yes, yes’ or ‘No, no.’ More than this is from the evil one.
Notes and References
"... In the Jewish tradition the call to truth-telling is also common. The Jewish expert, Montefiore, comments: "I do not think that the 'unbedingte Wahshaftigkeit im Reden' (unqualified truthfulness in speech) which Jesus demanded was not also demanded, and was not also regarded as part of the moral ideal, by the Rabbis.' Examples in Rabbinic literature include Ruth Rabbah 1:6& and Baba Mezia 49a. Finally, there is compelling evidence that 2 Enoch 49:l should not be utilized to support the Jewish oath formulation "yes, yes" since 1) this passage is missing in the shorter recension; 2) the work shows Christian influence; 3) the MSS date only from the 16th and 17th centuries; and 4) the type of swearing which is commanded ("yes, yes" or "no, no") is explicitly stated not to be an oath. Therefore, based upon the close connection of Mt. 5:34a and 37 and the unanimous witness of the early church, it seems best to understand Matthew as passing on Jesus' exhortation to speak the truth without relying upon an oath ..."
Deppe, Dean B. The Sayings of Jesus in the Paraenesis of James (p. 241) Academisch Proefschrift Vrije Universiteit Te Amsterdam, 1990