New Defender's Study Bible Notes
6:8 frontlets. Whether this commandment was intended to be taken physically or spiritually may be a question, but the Jews of later times understood these frontlets in terms of what they called phylacteries, small boxes containing passages of Scripture, which they wore on their foreheads when praying. See also Exodus 13:9,16. In any case, the essential teaching is that both the deeds of our hands and the thoughts of our minds should be constrained by the words of God, as recorded in Scripture.
6:9 posts of thy house. The custom of the Jews in respect to this command was to attach a small container with Deuteronomy 6:4 written on a scroll inside it to the door posts.