Why did David go back on his earlier vows to Mephibosheth (16:4)?
Apparently David feels justified in rejecting his earlier vow because he believes Mephibosheth (Jonathan’s son to whom David had promised protection and provision) is seeking to rebel against David and regain a portion of his grandfather’s kingdom. Sadly, David acted without hearing Mephibosheth’s side of the story. Ziba, acting in his own interests, had lied about Mephibosheth. It is the wise person who fully investigates a situation before acting (Proverbs 14:15).