Sirach 3:21
Ben Sira, Ecclesiasticus20 For great is the might of the Lord; but by the humble he is glorified. 21 Neither seek what is too difficult for you, nor investigate what is beyond your power. 22 Reflect upon what you have been commanded, for what is hidden is not your concern. 23 Do not meddle in matters that are beyond you, for more than you can understand has been shown you. 24 For their conceit has led many astray, and wrong opinion has impaired their judgment.
Mishnah Chagigah 2:1
MishnahOne may not expound the topic of forbidden sexual relations before three or more individuals; nor may one expound the act of Creation and the secrets of the beginning of the world before two or more individuals; nor may one expound by oneself the Design of the Divine Chariot, a mystical teaching with regard to the ways God conducts the world, unless he is wise and understands most matters on his own. The mishna continues in the same vein: Whoever looks at four matters, it would have been better for him had he never entered the world: Anyone who reflects upon what is above the firmament and what is below the earth, what was before Creation, and what will be after the end of the world. And anyone who has no concern for the honor of his Maker, who inquires into and deals with matters not permitted to him, deserves to have never come to the world.
Notes and References
"... While it is not stated in so many words, the writer [of Sirach] wants his readers to understand that the knowledge which they have already is an adequate guide for life, and there is no need to look for answers which are not readily available. One can presume that what is referred to here is the Law which man has in his possession as the source of all knowledge. This was a warning which was taken up at a later period by the rabbis and applied to those who would occupy themselves on matters of a mystical kind. Indeed, similar reserve is quite apparent in the mind of the author of the second part of Mishnah Hagigah 2:1, which lays down guidelines for the investigation of certain passages in Scripture. These provided the basis for speculations on the nature of God and the world which he has created. In fact the author goes much further than Ben Sirach and indicates that any one who occupied himself in such matters was in danger of imperiling his life ..."
Rowland, Christopher The Open Heaven: A Study of Apocalyptic in Judaism and Early Christianity (p. 75) Society for Promoting Christian Knowledge, 1982