Set a Guard Over My Mouth, O Lord

O Lord, I call to You; 
come quickly to me.
Here my voice when I call to You.
May my prayer be set before You like incense;
may the lifting up of my hand
be like the evening sacrifice.

Set a guard over my mouth, O Lord;
keep watch over the door of my lips.
Let not my heart be drawn to what is evil,
to take part in wicked deeds
with men who are evildoers;
let me not eat of their delicacies.

(Psalm 141:1-4)