Psalms 109:16-20

Here David gave reasons for his preceding requests. His enemy had practiced all the things David had asked God to do to him. He mercilessly persecuted the needy and the afflicted. He loved to curse other people rather than blessing them. Therefore the psalmist asked God to clothe him with cursing as with a garment and to make it as a belt that surrounded him always. Another interpretation is that the wicked man’s love for cursing was so much a part of him that David described it as if he wore cursing as a garment. [Note: VanGemeren, p. 694.] Psalms 109:19-20 are probably a prophetic statement rather than a continuation of the imprecation. [Note: Kidner, Psalms 73-150, p. 390; VanGemeren, p. 694.]

Sometimes David spoke of his "enemy" and sometimes of his "enemies" in this psalm. Evidently more than one person was in his mind. He may have spoken of an enemy in the singular when he thought of one of his enemies, perhaps the most hostile one. On the other hand, he may have used the singular to represent all of his enemies (a collective singular).