1 Samuel 15:27-28 contains a cute little parable meant to show that God has taken the kingdom from Saul.
Here's the lowdown. In this chapter, Saul disobeys God. Well, if we're being honest, Saul disobeys God in almost every chapter, but we're just trying to prove a point here. Saul was supposed to completely wipe out the Amalekites and their animals, however, he chose to let their king and their animals live.
Why you ask? Because he's Saul.
The prophet Samuel is very angry with Saul for his rebellion. Samuel's all like "how dare you let things be alive?" and Saul's all like "Ah c'mon man, be cool!" Samuel is so infuriated, he drops the word bomb and tells Saul that God has rejected him from being king.
When Samuel turns to leave, Saul grabs a part of his robe and a piece tears off. Samuel tells Saul that this is an example of how God has taken the kingdom from him and given it to someone else. The kingdom has been torn away from Saul just like the piece of robe has been torn away from Samuel.
Torn robes have a great significance in the Bible. Although it might not seem like a big deal, there's a longstanding tradition of broken clothes as a symbol of mourning and loss. Here's a small rundown in case you want to do some connecting the dots:
• Reuben tears apart his clothes when Joseph is not in the pit (Genesis 37:29)
• King David mourns for Abner (2 Samuel 3:31)
• The prophet's robe is torn into twelve pieces, representing the divide of the kingdom from Solomon (1 Kings 11:29-35)
• The high priest Caiaphas rips his robes at the blasphemy of Jesus (Matthew 26:62-65)
• Paul and Barnabas tear their robes as a sign of protest against the pagans (Acts 14:11-15)