1 Chronicles 29:3, commentary and pictures

Near the end of his life David summoned the princes of Israel with representative men from all parts of the kingdom to entrust to them what he had provided for God's house, giving his dying charge and securing their agreement and support for the great work. Although physical weakness made his personal presence unexpected, he was strengthened to address the people a final time with more than usual fervor and power. He told them of his own desire to build the temple and of the Lord's direction that the work should be committed to Solomon his son, with the assurance that Solomon would build His house and courts and his kingdom would be established forever if he remained constant in obedience. He charged all Israel to keep and seek all God's commandments so they might possess the good land and leave it to their children forever.

Although David gathered materials and made extensive preparations for the temple, God assigned the actual building to Solomon; David's part was to advise, counsel and encourage his son while the younger man carried out the work. David's affection, love and devotion for God's house moved him to give from his own personal wealth and treasury. That personal gift was over and above all he had already prepared, gathered and supplied for the holy house. The additional personal gift was three thousand talents of gold of Ophir and seven thousand talents of refined silver for the temple.

By giving personally, David set an example that led the people to follow and give willingly. The verse illustrates a special freewill offering for God's house, distinct from regular systematic contributions. Such offerings support God's service and are for the good of the people.