Solomon was instructed; partly by his father David, and partly by the Spirit of God, which inspired and guided him in the whole work. Or, these were Solomon's foundations, the Hebrew verb being put for the noun, as it is elsewhere. The sense is, These were the measures of the foundations upon which he intended to build the temple. After the first measure, i.e. according to the measure of the first and ancient cubit. By which it is evident that there were cubits of different sorts and sizes; which also appears from Ezekiel 40:5, Ezekiel 43:13. But how big those cubits were, and how much larger than the common cubits, and whether this was the cubit used by Moses in the building of the tabernacle, which seems most probable, or some other and yet larger cubit, is not agreed among learned men, and cannot now be exactly known, nor is it of any great moment for us to know.
Related Commentaries of 2 Chronicles 3:3
2 Chronicles 3:3
3 Now these are the things wherein Solomon was instructedb for the building of the house of God. The length by cubits after the first measure was threescore cubits, and the breadth twenty cubits.