תהילים נה:כא פירוש: רש״י

He stretched forth his hands This refers to Ahithophel the wicked.

He stretched forth Heb. שלח, tandit or tondet in Old French, stretched forth, tendait in modern French.

against him who was at peace with him Heb. בשלמיו, against him who was tranquil and at peace with him.