Paul assures Timothy that false teachings will not succeed. He emphasizes the importance of being pure (see 3:9).
firm foundation: This metaphor emphasizes safety from destruction (Isaiah 28:16). It may suggest a temple (see also 1 Timothy 3:15; 1 Corinthians 3:11; Ephesians 2:20; 1 Peter 2:4–7; Revelation 21:14).
The Lord knows: This quote refers to Numbers 16:5.
"Everyone who calls on the name of the Lord must turn away from iniquity": See Isaiah 52:11; compare Numbers 16:26–27; Leviticus 24:16; Psalm 6:8.