Which preposition to use with asseverate

to Occurrences 2%

VI Upon what Patricia said to the colonel in the drawing-room, what Joe Parkinson blurted out in the hall, and chief of all, what Roger Stapylton asseverated to Rudolph Musgrave in the library, after the other guests had gone, it is unnecessary to dwell in this place.

from Occurrences 1%

He had, however, asseverated from the beginning that he was the Consul of Spain at Charlestona fact not believed, because there was already a Consul resident at that place.

with Occurrences 1%

I might asseverate with passionate disgust and disdain: "The man who is capable of writing sonnets as well as triolets is capable of climbing an omnibus while holding an umbrella."

Which preposition to use with  asseverate