Psalm 141

Deliverance from wickedness........my own, and that of others.

Often, David prays against the wicked.....for their judgement to fall fast upon them, in order that God's name be preserved.  He does so here too, but first he very humbly seeks his own correction before the Lord.

He seeks God's attention, asking that his prayers be pleasant to Him, as incense on the alter.  He seeks to approach God rightly, and asks for the Lord's watch over his own mouth to keep him from falling into the wicked ways of those that surround him.  He knows the power of temptation, and asks for help before it strikes.

"Let he righteous strike me"....  The rebuke of righteous brothers is a blessing.  He asks for help in seeing this and not refusing wise counsel.   He knows what God has said He will do to the wicked, how He will judge them, and he doesn't want to fall in that group.

Then, after guarding himself with these prayers, he asks for that judgement to fall.

"my prayer is against the deeds of the wicked."

But.....David's "eyes are upon ....the Lord."   And as such, he will be helped.  The wicked will fall into their own traps, for they do not seek the Lord, or follow His ways.   But the righteous....will escape by God's help.