Moses said that G-d would say, "For I raise My hand to heaven [in order to swear,] and say, 'I live forever....'"
The Hebrew word for "forever" literally means "for the word," i.e., "as long as the world exists." In other words, G-d is here vowing that, no matter what the circumstances, His presence will always be "in the world," accompanying the Jewish people.
Whatever our tribulations, He will never forsake us.
We should therefore never fall into the conceptual trap known as "deism" -- the assumption that G-d, after having created the world, retreated into heaven, from where He merely passively observes the world running according to the brute laws of nature.
Rather, this verse tells us to remain confident that G-d is involved in our lives. He feels the pain of our exile, and -- as He promises in the verses that follow this one -- He will soon redeem us and the whole world.
Daily Wisdom Vol. 2