be insincere with

I do not intend to be insincere with you, my dear sir," I answered, "for I know how much better it is to be open on matters that are of a common interest in a family, than to affect mysteriousness.

"Jeffrey, I didn't think you'd be insincere with me."

I mustn't be insincere with God.

Because she was desperately in love she was forced to be insincere with Craven.

Poor dear Tilly! she would never see thirty again; and she need hardly have troubled, thought Polly, to be insincere with her.