20 My son, keep your father’s command
and do not forsake your mother’s teaching.
21 Bind them always on your heart;
fasten them around your neck.
“Father’s command… mother’s teaching” suggest parental unity and shared responsibility. Each has sought, in their own way, to set their child up for success in life. This they have done well, as the rest of the chapter shows, by teaching him how – not just what – to think. They have made wisdom the goal of obedience, rather than conformity, so that he will be prepared for whatever life brings his way. You will find no such talk as “because I said so,” instead their instruction is grounded in consideration of options.
“Bind them always on your heart; fasten them around your neck.” The heart is the center of the private life, while the neck is where things are publicly displayed. Integrity between public and private life is important, without which life becomes unnecessarily complicated. Treasure the wisdom you have, display it with honor, and you will add consistency to your defense from temptation.