Israel - comprising the before disunited (Heb 8:8) ten tribes’ kingdom, and that of Judah. They are united in the spiritual Israel, the elect Church, now: they shall be so in the literal restored kingdom of Israel to come.
I will put - literally, “(I) giving.” This is the first of the “better promises” (Heb 8:6).
mind - their intelligent faculty.
in, etc. - rather, “ON their hearts.” Not on tables of stone as the law (2Co 3:3).
write - Greek, “inscribe.”
and I will be to them a God, etc. - fulfilled first in the outward kingdom of God. Next, in the inward Gospel kingdom. Thirdly, in the kingdom at once outward and inward, the spiritual being manifested outwardly (Rev 21:3). Compare a similar progression as to the priesthood (1) Exo 19:6; (2) 1Pe 2:5; (3) Isa 61:6; Rev 1:6. This progressive advance of the significance of the Old Testament institutions, etc., says Tholuck, shows the transparency and prophetic character which runs throughout the whole.