Every claim presented to the executor or administrator shall be verified by the affidavit of the claimant, or some one on his behalf who has personal knowledge of the facts, to the effect that the amount claimed is justly due; that no payments have been made thereon, except as stated; and that there is no just counterclaim to the same, to the knowledge of the affiant. When it appears or is alleged that there is any written evidence of such claim the same may be demanded by the executor or administrator, or he may demand that its nonproduction be accounted for.