And Nathan said to the king, Go, do all that is in thine heart; for the LORD is with thee.

Wesley's Notes

7:3 Nathan said - Pursue thy intentions, and build an house for the ark. The design being pious and the thing not forbidden by God, Nathan hastily approves it, before he had consulted God about it, as both he and David ought to have done in a matter of so great moment. And therefore Nathan meets with this rebuke, that he is forced to acknowledge his error, and recant it. For the holy prophets did not speak all things by prophetic inspiration, but some things by an human spirit.

Jamieson-Fausset-Brown Bible Commentary

3. Nathan said to the king, Go, do all that is in thine heart-The piety of the design commended it to the prophet's mind, and he gave his hasty approval and encouragement to the royal plans. The prophets, when following the impulse of their own feelings, or forming conjectural opinions, fell into frequent mistakes. (See on [267]1Sa 16:6; [268]2Ki 4:27).

Matthew Henry's Concise Commentary

7:1-3 David being at rest in his palace, considered how he might best employ his leisure and prosperity in the service of God. He formed a design to build a temple for the ark. Nathan here did not speak as a prophet, but as a godly man, encouraging David by his private judgment. We ought to do all we can to encourage and promote the good purposes and designs of others, and, as we have opportunity, to forward a good work.