וַהֲכִינוֹתִ֥י אֶת־מַלְכוּת֖וֹ עַד־לְעוֹלָ֑ם אִם־יֶחֱזַ֗ק לַעֲשׂ֛וֹת מִצְוֺתַ֥י וּמִשְׁפָּטַ֖י כַּיּ֥וֹם הַזֶּֽה׃
Asimismo yo confirmaré su reino para siempre, si él se esforzare á poner por obra mis mandamientos y mis juicios, como aqueste día.
Rashi
Be strong and of good courage in order that your kingdom endure as the Holy One, blessed be He, has promised you, (verse 7): “... and I shall prepare his kingdom to eternity if he strengthens himself to perform My commandments, etc.”