Psalm 81
This is another Psalm written to be played on the Gittith and is written by Asaph. Although this psalm appears to have been written with Passover terms, it has historically been linked with the Feast of Tabernacles (Leviticus 23.33-44). It appears so due to the reference of the blowing of the trumpet at the new moon festival, thus linking it with harvest.
This psalm calls the people to worship at the Feast (1-5), then God pronounces judgement on them for not being obedient to His word (6-16).
Verses 1-5-We are to enter into corporate worship with all we have whether that worship is seen in giving, singing, activity, work, or whatever. When we worship, God speaks.
Verses 6-7-God calls the people to remember Meribah. But, which one? The one at the beginning of the Exodus (Exodus 17.6-7) or at the end (Numbers 20.2-13)? This is the point of the Selah. Moses was obedient at the first and disobedient in the last. Because of his obedience, God blessed the nation. Because of his disobedience, God disciplined him.
Selah-Which do you choose? Pause and consider this: Today did you choose disobedience or obedience?
Verses 8-10-God calls the people to remember what He has done for them. In remembering they should only worship Him.
Verses 11-16-However, God states, they did not submit to God. God gave them over to their sin (Romans 1.18-32). He then tells them of the victory that is theirs if and when they obey.
As your desire to live a victorious life increases, you will want to obey God. If we do not submit to His authority, we will be defeated. It is only in giving our all to Him that we have victory in this life.