The Book of #Proverbs also contains #wisdom from sources other than Solomon.
Sayings of the #wise can be found in Proverbs 22:17-24:34. The words of #Agur are preserved in Proverbs 30:1-33. The instruction King #Lemuel's mother provided for him was recorded in Proverbs 31:1-31, including the description of the "worthy woman."
These sayings were deemed wise and important enough to be preserved and maintained among the wise sayings of Solomon, and we can also benefit greatly from them.