1 Chronicles 29:17
I know also, my God, that thou triest the heart, and hast pleasure in uprightness. As for me, in the uprightness of mine heart I have willingly offered all these things: and now have I seen with joy thy people, which are present here, to offer willingly unto thee.
God tries, searches, and examines the heart, and He has pleasure in uprightness. David spoke these words in prayer just before Solomon was inaugurated as king. In that prayer David declares that in the uprightness of his heart he willingly offered the materials for the temple, and that he had seen with joy the people who were present offering willingly to God. His gifts for the temple were offered willingly from an upright heart, and he rejoiced to see the people give willingly as well for the work of building the sanctuary.
Everything offered had first been provided by God and already belonged to Him, so the gifts were a return of His own. The people's wealth and riches came from God, and their offerings were made to God from what already belonged to Him. The willingness itself came from God moving hearts by His Spirit, and without that divine work human effort could not have built the temple. Without His power moving their hearts, the king's efforts could not have succeeded, for their willingness and everything they offered came from God, who had provided their riches and moved their hearts. The people's willing generosity reflected hearts turned toward Him.
David goes on to ask God to preserve the people's devotion and to give Solomon a faithful heart to keep God's commandments and build the temple. He asks God to preserve their devotion and give Solomon a heart faithful to God's commandments, that Solomon might keep them and build the temple. Fidelity to God, with purity and humility before Him, is a person's strength, while outward display provides no true strength. The heart must be truly purified from sin and moral defilement, since outward polish, professed acceptance of truth, or skill in explaining belief cannot make a person pure while sin is cherished within. No outward religious appearance or nominal acceptance of truth can hide inward corruption from God; the heart must be purified by having truth planted within so that it governs the life.
The penitent takes this truth to heart by desiring to live with a sincere heart before God. Believers can use its language to express confidence that God knows the heart and sees faithful service, and to keep following Jesus without discouragement when faithfulness brings suffering.