1 Kings 10 when people bring you wealth, they are not doing this out of generosity. They already have everything they wanted, and they are buying your subservience. Sheba complemented King Solomon that he is twice as smart than she heard about him. He promised to give her everything she wanted. This is a blank check. He failed the test.
Do not swear on anything.
His downfall came quickly in 1 Kings 11. He always promised to do everything for the hundreds of princess wives and concubines he had, and they asked him to build temples and altars and statues for their gods.
See Proverbs 5 and 7.