Mark 7:3
For the Pharisees, and all the Jews, except they wash their hands oft, eat not, holding the tradition of the elders.
Cross-reference
Mark 7:13 concludes the same argument: tradition nullifies God's word, directly linking to the handwashing practice described here.
Mark 7:8 directly accuses: 'You leave God's commandment and hold to human tradition,' building on the tradition introduced here.
Matthew 15:2-6 is the parallel account where Jesus contrasts tradition with God's command about honoring parents.
Matthew 15:20 concludes that eating with unwashed hands does not defile, directly addressing the tradition in Mark 7:3.
Colossians 2:21-23 describes ascetic rules as human precepts, similar to the handwashing tradition of the elders.
Galatians 1:14 shows Paul's former zeal for the same 'traditions of my fathers' that Mark describes.
Colossians 2:8 warns against human tradition that contradicts Christ, echoing the critique of tradition in Mark.
1 Peter 1:18 speaks of being ransomed from futile inherited traditions, like the elders' tradition here.