Which preposition to use with untrembling

as Occurrences 2%

It was in no normal state of ordinary waking senses that the work went onwith never a downward look, nor even up, eyes riveted to the patch of snow on which the mittened hands fell as steady and untrembling as steel hammers.

at Occurrences 1%

On parchment, scroll and creed, With human life blood red, Untrembling at the deed, Plant firm your manly tread; The priest may howl, the jurist rave, But we will free the fettered slave.

Which preposition to use with  untrembling