I just checked this in the old Linear Chumash with Rashi (the blue one) and with R’ Hirsch’s Commentary. The Linear Chumash translates ?????? as “prostrated himself” on their graves. R’ Isaak Levy’s translation is “went to pray on the graves of the forefathers for strength.” Neither makes any mention of davening TO the Avos, just that he went to the graves to pray.
