Nathan had been giving to David, on God’s behalf, sundry exceeding great and precious promises. David expresses his gratitude to God for having so promised, and he says,

Now, O Lord God, the word that Thou hast spoken concerning Thy servant, and concerning his house, establish it for ever, and do as Thou hast said. 2 Samuel 7:25

Such words will be equally in place, if they shall be adopted by us in these modern times, and if, after reading a promise, on turning to God’s Word, we should finish by saying, “Remember the word unto Thy servant, upon which Thou hast caused me to hope,” it will be a practical application of the text, “Do as Thou hast said.”

How important it is to know what God has said, for unless we know what God has said, it will be folly to say, “do as thou hast said.” Perhaps there is no book more neglected in these days than the Bible… I beseech you, therefore,…if you have but little time, do not expend it in reading ephemeral books, but take your Bible and read it constantly; and I promise you one thing, that if you are already Christians, the more you read the Bible the more you will love it. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0088.cfm