Amsal 3:3

3:3 Do not let truth and mercy ¹  leave you;

bind them around your neck,

write them on the tablet of your heart. ² 

Amsal 3:21

3:21 My child, do not let them ³  escape from your sight;

safeguard sound wisdom and discretion. ⁴ 

[3:3]  ¹ tn The two words חֶסֶד וֶאֶמֶת (khesed ve’emet, “mercy and truth”) form a nominal hendiadys, the second word becoming an adjective: “faithful covenant love” or “loyal [covenant] love and faithfulness.”

[3:3]  ² sn This involves two implied comparisons (hypocatastasis). One is a comparison of living out the duties and responsibilities taught with binding a chain around the neck, and the other is a comparison of the inward appropriation of the teachings with writing them on a tablet. So the teachings are not only to become the lifestyle of the disciple but his very nature.

[3:21]  ³ tn The object of the verb “escape” is either (1) wisdom, knowledge, and understanding in vv. 13-20 or (2) “wisdom and discretion” in the second colon of this verse. Several English versions transpose the terms “wisdom and discretion” from the second colon into the first colon for the sake of clarity and smoothness (e.g., RSV, NRSV, NIV, TEV, CEV).
NIV takes the subject from the second colon and reverses the clauses to clarify that.

[3:21]  ⁴ tn Or: “purpose,” “power of devising.”