What does the Bible say about self-examination among believers?

In John 13, the disciples asked, 'Lord, is it I?' which reflects a heart posture of humility and self-reflection. This spirit of self-examination is highlighted in Philippians 3:3, where Paul speaks of having no confidence in the flesh. The Holy Spirit works in believers to foster a sense of suspicion about themselves rather than others, leading them to recognize their sin nature and dependence on God's grace. By asking, 'Lord, is it I?', individuals acknowledge their need for sanctification and understanding that they are capable of sin without God's intervention.