I am vouching for his character as a trustworthy individual.
vouching in favor
Frequency:
45
%
I am vouching in favor of her promotion.
vouchsafe
Frequency:
30
%
He vouchsafed a smile to his loyal followers.
Idiomatic Expressions for vouch
Phrase: vouchsafe
Meaning: to grant or give something as a favor or a privilege
Usage: The king vouchsafed the knight a title and lands for his bravery in battle.