Which preposition to use with regardful

of Occurrences 17%

His brother, in the last action with the Spaniards, having not done his duty, was, at Blake's desire, discarded, and the ship was given to another; yet was he not less regardful of him as a brother, for, when he died, he left him his estate, knowing him well qualified to adorn or enjoy a private fortune, though he had found him unfit to serve his country in a publick character, and had, therefore, not suffered him to rob it.

Which preposition to use with  regardful