(Read Daniel 9:4-19)

In every prayer we must make confession, not only of the sins we have been guilty of, but of our faith in God, and dependence upon him, our sorrow for sin, and our resolutions against it. It must be our confession, the language of our convictions. Here is Daniel’s humble, serious, devout address to God; in which he gives glory to him as a God to be feared, and as a God to be trusted. We should, in prayer, look both at God’s greatness and his goodness, his majesty and mercy. Here is a penitent confession of sin, the cause of the troubles the people for so many years groaned under. All who would find mercy must thus confess their sins. Here is a self-abasing acknowledgment of the righteousness of God; and it is evermore the way of true penitents thus to justify God. Afflictions are sent to bring men to turn from their sins, and to understand God’s truth. Here is a believing appeal to the mercy of God. It is a comfort that God has been always ready to pardon sin. It is encouraging to recollect that mercies belong to God, as it is convincing and humbling to recollect that righteousness belongs to him. There are abundant mercies in God, not only forgiveness, but forgivenesses. Here are pleaded the reproach God’s people was under, and the ruins God’s sanctuary was in. Sin is a reproach to any people, especially to God’s people. The desolations of the sanctuary are grief to all the saints. Here is an earnest request to God to restore the poor captive Jews to their former enjoyments. O Lord, hearken and do. Not hearken and speak only, but hearken and do; do that for us which none else can do; and defer not. Here are several pleas and arguments to enforce the petitions. Do it for the Lord Christ’s sake; Christ is the Lord of all. And for his sake God causes his face to shine upon sinners when they repent, and turn to him. In all our prayers this must be our plea, we must make mention of his righteousness, even of his only. The humble, fervent, believing earnestness of this prayer should ever be followed by us.

For a more detailed summary select the link below.
Daniel 9 Bible Commentary – Matthew Henry (concise) (christianity.com)

Daniel 9:9

⁹ To the Lord our God belong mercies and forgiveness; for we have rebelled against him.