Who became jealous of David?

King Saul became jealous of David due to David's rising popularity and success, particularly after he defeated Goliath and the women sang praises of David, stating that he had slain "tens of thousands" while Saul had only slain "thousands." This jealousy intensified as David continued to gain favor with the people and was seen as a threat to Saul's throne. Saul's jealousy ultimately led to a series of attempts to kill David.