Albert Barnes Commentary Job 38:6

"Whereupon were the foundations thereof fastened? Or who laid the corner-stone thereof," — Job 38:6 (ASV)

On what are the foundations - Margin, “sockets.” The Hebrew word (אדן 'eden) means “a basis,” as of a column, or a pedestal; and then also the foundation of a building. The language here is evidently figurative, comparing the earth with an edifice. In building a house, securing a proper foundation is essential to its stability; and here God represents himself as rearing the earth on the most permanent and solid basis. The word is not used in the sense of sockets, as it is in the margin.

Fastened - Margin, “made to sink.” The margin rather expresses the sense of the Hebrew word הטבעוּ hāṭâba‛û. It is rendered “sink” and “sunk” in Psalms 69:2, Psalms 69:14; Psalms 9:15; Lamentations 2:9; Jeremiah 38:6, Jeremiah 38:22; “drowned” in Exodus 15:4; and were settled in Proverbs 8:25. The word does not occur elsewhere in the Scriptures, and the prevailing sense is that of “sinking,” or “settling down,” and hence, to “impress”—as a seal “settles down” into wax. The reference here is to a foundation-stone that sinks or settles down into clay or mire until it becomes solid.

Or who laid the corner stone of it - Still an allusion to a building. The cornerstone sustains the principal weight of an edifice, as the weight of two walls is concentrated on it, and hence, it is of such importance that it should be solid and firmly fixed. The question proposed for Job's solution is, On what is the earth founded? On this question a great variety of opinions were entertained by the ancients, and of course no correct solution could be given of the difficulty. It was not known that it was suspended and held in its place by the laws of gravitation. The meaning here is, that if Job could not solve this inquiry, he ought not to presume to sit in judgment on the government of God, and to suppose that he was qualified to judge of His secret counsels.