He begins by asking God to provide wisdom and righteousness in Solomon's heart. Being king is not as easy as it looks.
Then he asks for the natural elements to bring blessings to the nation. Water for good crops is just the beginning. He calls for righteousness and defense for afflicted people and salvation for the children of the needy.
He prays for his territory to increase, that he will rule "from sea to sea and from the River to the ends of the earth."(For details of the succession to the Throne, see I Kings 1 and 2.)
Matthew Henry's Commentary says this is the last Psalm David wrote when he was dying. It is not the last as they are organized in the Book of Psalms.
This psalm shares the attitude of many in the modern world. Satan paints an inviting picture of the life of the wealthy and powerful, and Asaph was almost taken in by it. He envied the arrogant and he almost went for that kind of security.
He was troubled by his own thoughts, and he felt he had betrayed his office. When he went to the Sanctuary of God, he saw their final destiny. Money and power were deceptive and God alone was his strength. His greed for power and money had made him a brute beast, but in God, he was restored, and with the Sovereign Lord as his refuge, he would stay near God and tell of his deeds.
Asaph begins by addressing God with questions about why he has rejected Israel and directed his anger at them. He reminds God that the people he saved have been attacked by his foes in the place where Israel had worshiped him. He goes on to describe the destruction of the Temple and the humiliation of Israel. He laments that God has given no sign of hope and they are destitute. The prophets were all killed.
Asaph cites no signs of hope, but he retains his faith that God is still able to restore Israel. In vs. 12, he launches into a list of God's acts that saved them in the past. In vs. 22, he implores God to show his power again: "Rise up, O God, Defend your cause." He does not doubt God's authority or ability to rescue Israel from His adversaries.