Now David was old and full of days; and he made Solomon his son king over Israel.
"Four thousand praised Jehovah with the instruments that I (David) made"  (1 Chronicles 23:5).  David's actions in this had no prior command of God to justify it.  He violated the divine instructions that, "Ye shall not add unto the word which I command you, neither shall ye diminish from it"  (Deuteronomy 4:2).  David's invention of instruments of music and his introduction of them into the worship of God was specifically condemned by the prophet Amos (Amos 5:23; 6:5).  (We have discussed this in Vol. 1 of my commentaries on the Minor Prophets, Joel, Amos and Jonah, pp. 163-169,180-183.)