John Gill Commentary Psalms 118:11

"They compassed me about; yea, they compassed me about: In the name of Jehovah I will cut them off." — Psalms 118:11 (ASV)

They compassed me about; yea, they compassed me about
Which is repeated not only for the confirmation of, it, but to denote the frequency and fury of their attacks, and their obstinate persisting therein; (See Gill on Psalms 118:10);

but in the name of the Lord I will destroy them ;
which also is repeated to show the strength of his faith, and the continuance of it, notwithstanding his numerous enemies, and their violent efforts against him.