Undutiful

Lady Stair sent him for answer, that her daughter, sensible of her undutiful behaviour in entering into a contract unsanctioned by her parents, had retracted her unlawful vow, and now refused to fulfil her engagement with him.

Source: tatoeba (7752075)

For, as long as he liv’d, ’twas his comfort and joy, to think he’d not been an undutiful boy.

Source: tatoeba (11620127)

I know my duty; you are all undutiful: Lascivious Edward, and thou perjured George, And thou mis-shapen Dick, I tell ye all I am your better, traitors as ye are: And thou usurp’st my father’s right and mine.

Source: wiktionary

1652, George Herbert, A Priest to the Temple, or, The Countrey Parson, reproduced in George Herbert Palmer (ed.), The English Works of George Herbert, Boston: Houghton Mifflin, 1905, Volume 2, Chapter 6. The Parson Praying, p. 27, Besides his example, he, having often instructed his people how to carry themselves in divine service, exacts of them all possible reverence, by no means enduring either talking, or sleeping, or gazing, or leaning, or halfe-kneeling, or any undutifull behaviour in them, but causing them when they sit, or stand, or kneel, to do all in a strait and steady posture, as attending to what is done in the Church, and every one, man and child, answering aloud both Amen and all other answers which are on the Clerk’s and people’s part to answer […]

Source: wiktionary