protestation (n.)
solemn declaration, affirmation
AW V.iii.139 [King reading Diana's letter, of Bertram] Upon his many protestations to marry me when his wife was dead
Ham III.ii.145 [stage direction for dumb show, of the Queen and King] She kneels, and makes show of protestation unto him
LLL I.i.33 [Berowne to King, of his fellow-lords] I can but say their protestation over
Luc 1844 [of Brutus] he ... to his protestation urged the rest
TG I.ii.99 [Julia to Lucetta] Here is a coil with protestation [i.e. of love]