Deu 6:4 Hear, O Israel, Jehovah our God is one Jehovah. 5 And you shall love Jehovah your God with all your heart, and with all your soul, and with all your might.
6 And these words which I am commanding you today shall be on your heart..
7 And you shall teach them to your sons, and shall speak of them as you sit in your house, and as you walk in the way, and as you are lying down, and as you are rising up.
8 And you shall bind them for a sign on your hand; and they shall be for frontlets between your eyes.
9 And you shall write them on the doorposts of your house, and on your gates.
Although God said that His word was to be a sign bonded on the hand and that they should be a frontal on the forehead, it was God’s purpose to emphasize the meaning of God’s word in the hearts and minds of men: Jer 31:33 For this is the covenant that I will make with the house of Israel, after those days, saith Jehovah: I will put my law in their inward parts, and will write it in their heart; and I will be their God, and they shall be my people.
Isa 51:7 Listen to me, you who know righteousness, a people in whose heart is my law; do not fear the reproach of man, and do not be bowed from their blasphemings.
Heb 10:16 This is the covenant that I will make with them after those days, declares the Lord: I will put my laws in their hearts and will write them on their minds, Likewise: Hebr. 8:10 For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws in their minds and write them on their hearts. I will be their God, and they will be my people.
The Jews took these sentences literally; there was a little hole at the gate of the homes where these instructions were kept. Well, this beautiful custom cannot be blamed, though the most important thing is that the words is sank deep into people’s minds and hearts. The purpose was probably that people would study them in their minds and hearts. Luke 2:19 but Mary continued to treasure in her heart all these things and to ponder them. – When the Bible (2 Timothy 2:19) says that “The Lord knows those who are His,” it is not based on the fact that there is a small box on the person’s forehead that contains some Bible passages; the Lord and His angels see the minds (hearts) of the people. At present, we do not believe there is any thought or emotion in the heart, but they are in the minds of men, i.e. brains. Sometimes in the 1970s, Jehovah’s Witnesses seriously supported the literal interpretation of these Bible verses and witnessed strongly the thinking activity taking place in the heart.
Then: Law in heart and mind, not a little box on your forehead. The angels read from the brain of the men if they are the children of God or the beast’s own. For example, when God was appalled at the behavior of people in Sodom and Gomorrah, people were found out if they were righteous. Abraham insisted God to save the cities from destruction, if only a few of the townspeople could be found a few dozen of righteous people. These could not be found. Not because there were no small boxes on the foreheads of the people, but because the commandments of God had not fallen on people’s minds (hearts) or hearts and their hands (in the form of deeds).
Similarly, it is a matter of emblem when God sent angels to kill people who did not have the name of the Lord on the forehead. Eze 9:4 And Jehovah said to him, pass through in the midst of the city, in the midst of Jerusalem, and set a mark on the foreheads of the men who are groaning and are mourning over all the abominations that are done in her midst.
Read also the following articles on the subject.