51:13 The promises David made in this section of verses gave God reasons to grant forgiveness so they were indirect requests for pardon. If forgiven, David would show others how God deals with penitent sinners. He would do this as an example as well as verbally. Then sinners would turn to the Lord for deliverance.
51:14-15 "Bloodguilt"refers to guilt as a result of killing someone without divine authorization. When God saved him from this guilt and opened his lips by forgiving him, David would joyfully praise the Lord.
51:16-17 Third, David promised to sacrifice to Yahweh if God would forgive him. He would offer sacrifices of worship, but he acknowledged that what God really wanted, and what he would also offer, was a different attitude (cf. 50:7-15, 23). In David's case, there was no sin or trespass offering that he could present that God would accept. Since he had sinned with a high hand, in rebellious defiance of Yahweh and in repudiation of the terms of His covenant, his sentence was death (Num. 15:30-31; cf. 2 Sam. 12:9). The only reason he did not suffer this fate was God pardoned him. The prophet Nathan brought the news of God's special pardon to David (2 Sam. 12:13). God has already given His promise to pardon the guilt of any New Testament believer for any sin we may commit (1 John 1:9). The basis of this gracious pardon is the work of Jesus Christ on Calvary (1 John 1:7).
