What does Psalm 50:13 mean?

This continues God's accusation against Israel (Psalm 50:7). This involves their performance of sacrifices (Psalm 50:8), which God rejects (Psalm 50:9). Later, the Lord will explain that Israel's sinful disobedience proves their sacrifices are hollow, empty, and robotic. They mistake following rituals with honoring their God (Psalm 50:16–21). God has noted that He doesn't need to be given anything; He already owns everything (Psalm 50:10–11).

In a moment of dry humor, God also points out that He wouldn't need to tell His creations if He were hungry (Psalm 50:12)—which He cannot be, as a perfect spirit (John 4:24). Now He reminds them that He doesn't consume those sacrifices as food. That is not the purpose for which He instituted those sacraments (Exodus 29:38–42; Leviticus 16:11–14). They were meant to remind Israel of their need for God's forgiveness. Sacrifice, accompanied by faith, was a form of obedience demonstrating a repentant, God-honoring heart.

As later verses will explain, Israel's sacrifices are not sincere. They sin and disobey God, then rely on rituals to make themselves right with the Lord (Psalm 50:16–21).