Proverbs 6:21 New English Translation

²¹Bind them^[a] on your heart^[b] continually;
fasten them around your neck.

Proverbs 6:21 sn The figures used here are hypocatastases (implied comparisons). There may also be an allusion to Deut 6 where the people were told to bind the law on their foreheads and arms. The point here is that the disciple will never be without these instructions. See further, P. W. Skehan, Studies in Israelite Poetry and Wisdom (CBQMS), 1-8.
Proverbs 6:21 sn The Hebrew word לֵב (lev) “heart” includes the mind. Hebrew does not separate “heart knowledge” and “head knowledge.” While “heart” may convey a deep commitment, the “mind” is crucial to considering and adopting the instruction. To have the instruction “on your mind” is critical to the deliberate talking to oneself needed to conform to the instruction, to meditating on it and assimilating it into one’s world view.

New English Translation (NET)