Isaiah 40:12

מִי־מָדַד בְּשָׁעֳלוֹ מַיִם וְשָׁמַיִם בַּזֶּרֶת תִּכֵּן וְכָל בַּשָּׁלִשׁ עֲפַר הָאָרֶץ וְשָׁקַל בַּפֶּלֶס הָרִים וּגְבָעוֹת בְּמֹאזְנָיִם׃

12 Who has measured in the hollow of his hand the waters? Or measured the heavens with his hand? Or held in a basket the dust of the earth? Or weighed the mountains in a scales? Or the hills in a balance?

מִי־מָדַד בְּשָׁעֳלוֹ מַיִם  Who has measured in the hollow of his hand the waters? The great Isaiah scroll from Qumran has מי ים "the water of the sea" here. It is a good reading? It certainly makes sense, but with no other manuscript to support it, we will leave the MT as it is. שֹׁעַל is a "handful," or "the hollow of the hand." Even-Shoshan lists three occurrences: 1 Kings 20:10; Isaiah 40:12 and Ezekiel 13:19.

וְשָׁמַיִם בַּזֶּרֶת תִּכֵּן  Or measured the heavens with his hand? The "span" (זֶרֶת) is the breadth of the hand with the fingers splayed far apart. This was the measurement of the breastplate that the high priest wore with twelve precious stones for each of the twelve tribes (Exodus 28:16; 39:9). So the image is of God laying out his hand and getting the entire sky within his grasp

וְכָל בַּשָּׁלִשׁ עֲפַר הָאָרֶץ  Or held in a basket the dust of the earth? The basket here, the שָׁלִשׁ, is a fraction of something, probably a "third" (shalosh) the way we talk about a "quart." The verb  וְכָל (qal vav-consecutive perfect 3 ms sg from the pe-ayin verb כּוּל, "sustain, contain") is not to be confused with the noun כֹּל "all." The verb falls into the pattern of קוּם, cf. Weingreen pp. 270-271.

וְשָׁקַל בַּפֶּלֶס הָרִים וּגְבָעוֹת בְּמֹאזְנָיִם׃    Or weighed the mountains in a scales?  Or the hills in a balance?  A "scales" (Hebrew פֶּלֶס peles) and a "balance" (מֹאזְנָיִם me’oznaim) are simply different parts of what we would think of as a typical scale. The peles is the beam that swings, and the two me’oznaim (note the dual form) are the pans that hold the items being measured.  These are the kind of questions God asked Job: "Have you comprehended the vast expanses of the earth? Tell me, if you know all this" (Job 38:18). "Who can tip over the water jars of the heavens when the dust becomes hard and the clods of earth stick together?" (Job 38:37-38).

Unlike the questions for Job, these are the awed reverences of the believing prophet, who loves this shepherd-warrior and who knows that he is the creating God.